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Structures and Pointers
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### Array Cont

1. Program: WAP initialization each element of array individually. Solution: #include<conio.h> #include<stdio.h> void main( ) { int r[5]; clrscr( ); r[0] = 10; r[1] = 20; r[2] = 30; r[3] = 60; r[4] = 70; printf(“Rvalueis =%d”, r[3]); getch(); } OUTPUT: R valueis = 60 Program : #include<conio.h> #include<stdio.h> void main() { int r[5], t; clrscr(); r[0]=60; r[1]=50; r[2]=40; r[3]=60; r[4]=10; t = r[0] + r[1]+r[2]+r[3]+r[4]; printf(“Totalis =%d”,t); getch(); } OUTPUT: Total is = 220
2. Program: #include<conio.h> #include<stdio.h> void main() { int r[5] , t , i; clrscr(); t = 0; r[0]=10; r[1] = 20; r[2] = 30; r[3] = 30; r[4] = 60; for(i = 0; i<5; i++) { t = t + r[i]; printf(“Totalis =%d”,t); } getch(); } OUTPUT: Total is = 130 Program: WAP finding out thesumof odd and even numbers in array. Solution: #include<conio.h> #include<stdio.h> void main() { int arr[]={2,7,8,9,11}; int sumev = 0; int sumodd = 0; int i; for(i=0;i<5;i++) {
3. if((arr[i]%2)==0) sumev = sumev + arr[i]; else sumodd = sumodd + arr[i]; } printf(“Sumof even numbers in array =%d”, sumev); printf(“Sumof odd numbers in array =%d”, sumodd); getch(); } OUTPUT : Sum of even numbers in array = 10 Sumof odd numbers in array = 27 Program: Displaying thelength of an array. Solutions: #include<conio.h> #include<stdio.h> void main() { doublemarks[]={4.5,7.8,9.9,8.9}; int n; clrscr(); n = marks. length; printf(“Lengthis = %d”,n); getch(); } OUTPUT: Length is = 4
4. Program: WAP Display theelements of an array. Solution: #include<conio.h> #inlcude<stdio.h> void main() { char alpha[] = {‘A’,’B’,’C’,’D’,’E’}; int n = alpha . length; printf(“Element of Array”); for(int i = 0; i<n; i++) printf(alpha[i]); getch(); } OUTPUT : Element of Array A B C D E Program : WAP display arrangingthenumber in descendingorder. Solution: #include<conio.h> #include<stdio.h> void main() { int a[] = {20, 5, 70, 100, 14}; clrscr(); int n = a . length; int temp, i, j; for(i=0;i<n;i++) { for(j = i + 1; j<n; j++) { if(a[i]<a[j])
5. { temp = a[i]; a[i] = a[j]; a[j] = temp; } } } printf(“Numbers in descendingorder”); for(i = 0; i<n; i++) { printf(“%d”,a[i]); } getch(); } OUTPUT : Numbers in descending order 100 70 20 14 5 Program : WAP sorting a characterarray usingsort() function. Solution: #include<conio.h> #include<stdio.h> void main() { char name[]={‘S’,’A’,’R’,’N’}; Arrays.sort(name); printf(“Elements in ascendingorder”); for(int i = 0; i<name.length;i++) printf(“%c”,name[i]);
6. getch(); } OUTPUT : Elements in ascending order A R N S Program : WAP sorting an integer array usingsort() function. Solution: #include<conio.h> #include<stdio.h> void main() { int num[]={70,56,29,4,750,200,50}; int n; int i; Arrays.sort(num); printf(“Elements in ascendingOrder”); for(i = 0; i<n; i++) printf(“%d”,num[i]); getch(); } OUTPUT: Elements in ascendingOrder 4 29 50 56 70 200 750 Two – DimensionalArray: You can createarray in form of m x n matrix or in table formalso. Syntax : Data Type arrayname[] [] = new type[size] [size]; Example : int matrix[] [] = new int[3][5];
7. 3 Rows 5 Columns Program: #include<stdio.h> #include<conio.h> void main() { int a[] [] = {{55,29,17},{70,56,25},{69,75,23},{7,8,9}}; int i, j; clrscr(); printf(“Martix= “); for(i = 0;i<3; i++) { for( j = 0; j<3 ; j++) { printf(“%d”,a[i][j],””); } printf(“n”); } getch(); } OUTPUT : Matrix = 55 29 17 70 56 25 69 75 23 7 8 9 Program : WAP showing that you can use literalvalues as well as expressions inside { } for initialization. [0] [0] [0] [1] [0] [2] [0] [3] [0] [4] [1] [0] [1] [1] [1] [2] [1] [3] [1] [4] [2] [0] [2] [1] [2] [2] [2][3] [2] [4]
8. Solution: #include<conio.h> #include<stdio.h> void main() { int a[] [] ={{5*2, 2*1,3*0},{6*3,7*0,9*4},{5*3,5*5,4*9}}; int i, j; clrscr(); for(i = 0; i<3; i++) { for( j = 0; j<3; j++) { printf(“%d”,a[i][j],””); printf(“n”); } } getch(); } OUTPUT : 10 2 3 18 0 36 15 25 36 Three- Dimensional Array : 3-Dimensionalarray means array with multiple dimensional3, 4 or even more. Example : int three[2] [4] [6]; Program : #include<conio.h> #include<stdio.h> void main() { int three[2][4][6];
9. int i, j, k; for(i = 0; i<3; i++) { for( j = 0; j<4; j++) { for( k = 0; k<5 ; k++) { three[i][j][k] = i * j * k; } } } for(i = 0; i<3; i++) { for( j = 0; j<4; j++) { for( k = 0; k<5; k++) { printf(three[i][j][k], “”); printf(“n”); } printf(“n”); } getch(); } Question 1: WAP to input values into an array and display them.
10. 2: WAP to add elements of an array.
11. 3: WAP to count even and odd numbers in an array.
12. 4: WAP to pass array elements to a function.
13. 5: WAP to input and display a matrix.
14. Session – 6 Function A function is a group of statements that together perform a task. Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions. You can divide up your code into separate functions. How you divide up your code among different functions is up to you, but logically the division is such that each function performs a specific task. A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.
15. Defining a function: The general form of a function definition in C programming language is as follows – return_type function_name( parameter list ) { body of the function } Return Type: A function may return a value. The return_type is the data type of the value the function returns. Some functions perform the desired operations without returning a value. In this case, the return_type is the keyword void. Function Type: This is the actual name of the function. The function name and the parameter list together constitute the function signature. Parameters: A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. Parameters are optional; that is, a function may contain no parameters. Function Body: The function body contains a collection of statements that define what the function does. Example: /* function returningthemax between two numbers */
16. int max(int num1, int num2) { /* local variabledeclaration */ int result; if (num1 > num2) result = num1; else result = num2; return result; } Function Declaration: A function declaration tells the compiler about a function nameand how to callthe function. Theactualbody of the function can be defined separately. return_typefunction_name( parameterlist ); For theabove defined functionmax(), thefunction declaration is as follows – int max(int num1, int num2); Parameter names are not important in functiondeclaration only their typeis required, so thefollowing is also a valid declaration – int max(int, int); Callinga Function: When a programcalls a function, the program control is transferredtothe called function. Acalled function performs a defined task and when its return statementis executed or when its function-ending closing brace is reached, it returns the program control back to the main program. To call a function, you simply need to pass the required parameters along with the function name, and if the function returns a value, then you can store the returned value. Program:#include <stdio.h> /* function declaration */
17. int max(int num1, int num2); int main () { /* local variable definition */ int a = 100; int b = 200; int ret; /* calling a function to get max value */ ret = max(a, b); printf( "Max value is : %dn", ret ); return 0; } /* function returning the max between two numbers */ int max(int num1, int num2) { /* local variable declaration */ int result; if (num1 > num2) result = num1; else result = num2; return result; } OUTPUT :Max value is : 200 Function Arguments: If a function is to use arguments,it must declarevariables that accept the values of the arguments. These variables are called the formal parameters of the function. Formal parameters behavelike other local variables inside the function and are created upon entry into the function and destroyed upon exit. While calling a function, therearetwoways in which arguments can be passed to a function –
18. Sr.No . Call Type & Description 1 Call By Value This method copies the actual value of an argument into the formal parameter of the function. In this case, changes made to the parameter inside the function have no effect on the argument. 2 Call By Reference This method copies the address of an argument into the formal parameter. Inside the function, the address is used to access the actual argument used in the call. This means that changes made to the parameter affect the argument. Call By Value : The call by value method of passing arguments to a function copies the actual value of an argument into the formal parameter of the function. In this case, changes made to the parameter inside the function have no effect on the argument. By default, C programming uses call by value to pass arguments. In general, it means the code within a function cannot alter the arguments used to call the function. Consider the function swap() definition as follows. /* function definition to swap the values */ void swap(int x, int y) { int temp; temp = x; /* save the value of x */ x = y; /* put y into x */ y = temp; /* put temp into y */ return; }
19. Now, let us call thefunction swap() by passing actualvalues as in thefollowing example – #include<stdio.h> /* function declaration*/ void swap(int x, int y); int main () { /* local variabledefinition */ int a = 100; int b = 200; printf("Before swap, value of a : %dn", a ); printf("Beforeswap, value of b : %dn", b ); /* calling a function toswap thevalues */ swap(a, b); printf("After swap, valueof a : %dn", a ); printf("After swap, valueof b : %dn", b ); return 0; } OUTPUT : Before swap, value of a :100 Before swap, valueof b :200 After swap, value of a :100 After swap, value of b :200
20. Call by Reference: Thecall by reference method of passing arguments to a function copies theaddress of an argument intotheformalparameter. Inside the function, the address is used to access the actual argument used in the call. It means the changes made to the parameter affect the passed argument. To pass a valueby reference, argumentpointers are passed to the functions just like any other value. So accordingly you need to declarethe function parameters as pointer types as in thefollowing function swap(), which exchanges the values of the two integer variables pointed to, by their arguments. Program : /* function definition to swap the values */ void swap(int *x, int *y) { int temp; temp = *x; /* save the value at address x */ *x = *y; /* put y into x */ *y = temp; /* put temp into y */ return; } Let us now callthe function swap() by passing values by referenceas in the following example − #include<stdio.h> /* functiondeclaration*/ void swap(int *x, int *y); int main () { /* localvariable definition */ int a = 100; int b = 200; printf("Beforeswap, value of a : %dn", a ); printf("Beforeswap, value of b : %dn", b ); /* calling a function toswap thevalues.
21. * &a indicates pointer to a ie. address of variablea and * &b indicates pointer to b ie. address of variableb. */ swap(&a, &b); printf("After swap, valueof a : %dn", a ); printf("After swap, valueof b : %dn", b ); return 0; } OUTPUT : Before swap, value of a :100 Before swap, value of b :200 After swap, value of a :200 After swap, value of b :100 Scope Rules: A scope in any programmingis a region of theprogram where a defined variable can have its existence and beyond that variable it cannot be accessed. There are three places where variables can be declared in C programming language −  Inside a function or a block which is called local variables.  Outside of all functions which is called global variables.  In the definition of function parameters which are called formal parameters. Let us understand what are local and global variables, and formal parameters. Local Variables: Variables that aredeclared inside a function or block are called local variables. They can be used only by statements that are inside that function or block of code. Local variables are not known to functions outside their own. Program : #include<stdio.h>
22. int main () { /* local variabledeclaration */ int a, b; int c; /* actual initialization */ a = 10; b = 20; c = a + b; printf ("valueof a = %d, b = %d and c = %dn", a, b, c); return 0; } OUTPUT: value of a = 10, b = 20, c = 30 Global Variable: Global variables are defined outside a function, usually on top of theprogram. Globalvariables hold their values throughout the lifetime of your programand they can be accessed insideany of the functions defined for the program. A global variable can be accessed by any function. Program: #include <stdio.h> int main () { /* local variable declaration */ int a, b; int c; /* actual initialization */ a = 10; b = 20; c = a + b;
23. printf ("value of a = %d, b = %d and c = %dn", a, b, c); return 0; } Program : #include <stdio.h> /* global variable declaration */ int g = 20; int main () { /* local variable declaration */ int g = 10; printf ("value of g = %dn", g); return 0; } Formal Parameters: Formal parameters, are treated as local variables with-in a function and they take precedence over global variables. Program: #include <stdio.h> /* global variable declaration */ int a = 20; int main () { /* local variable declaration in main function */ int a = 10; int b = 20; int c = 0; printf ("value of a in main() = %dn", a); c = sum( a, b); printf ("value of c in main() = %dn", c); return 0;
24. } /* function to add two integers */ int sum(int a, int b) { printf ("value of a in sum() = %dn", a); printf ("value of b in sum() = %dn", b); return a + b; } OUTPUT: value of a in main() = 10 value of a in sum() = 10 value of b in sum() = 20 value of c in main() = 30 Initializing Local and Global Variables: When a local variable is defined, it is not initialized by the system, you must initializeit yourself. Global variables are initialized automatically by the system when you define them as follows – Data Type Initial Default Value int 0 char '0' float 0 double 0 pointer NULL Passing Arrays as function arguments in “C”: If you want to pass a single-dimension array as an argument in a function, you would have to declarea formal parameter in one of following threeways and all
25. three declaration methods produce similar results because each tells the compiler that an integer pointer is going to be received. Similarly, you can pass multi-dimensional arrays as formal parameters. Way-1 Formal parameters as a pointer – void myFunction(int *param) { } Way-2 Formal parameters as a sized array – void myFunction(int param[10]) { } Way-3 Formal parameters as an unsized array − void myFunction(intparam[]) { } Program: double getAverage(intarr[], int size) { int i;
26. doubleavg; doublesum = 0; for (i = 0; i < size; ++i) { sum += arr[i]; } avg = sum / size; return avg; } Now, let us call theabove function as follows – #include<stdio.h> /* function declaration*/ double getAverage(intarr[], int size); int main () { /* an int array with 5 elements */ int balance[5] = {1000, 2, 3, 17, 50}; double avg; /* pass pointer to thearray as an argument */ avg = getAverage( balance, 5 ) ; /* output thereturned value*/ printf( "Averagevalue is: %f ", avg ); return 0; } OUTPUT: Average value is: 214.400000
27. Question 1: Display all prime numbers between two Intervals.
28. 2: Check Prime and Armstrong Number by making function.
29. 3: Check whether a number can beexpressed as thesum of two prime number.
30. 4: Writea programin C to find thesquareof any number using the function.
31. 5: Writea programin C to swap two numbers usingfunction.
32. Session-7 Structure Arrays allow to define type of variables that can hold several data items of the same kind. Similarly structure is another user defined data type available in C that allows to combine data items of different kinds. Structures are used to represent a record. Suppose you want to keep track of your books in a library. You might want to track the following attributes about each book –  Title  Author  Subject  Book ID Defining a Structure: To define a structure, you must usethe struct statement.Thestruct statement defines a new data type, with more than onemember. Theformat of the struct statement is as follows – struct Books
33. { char title[50]; char author[50]; char subject[100]; int book_id; }; AccessingStructure Members: #include<stdio.h> #include<string.h> structBooks { char title[50]; char author[50]; char subject[100]; int book_id; }; intmain() { structBooksBook1; /*DeclareBook1 of typeBook */ structBooksBook2; /*DeclareBook2 of typeBook */ /*book1 specification*/ strcpy(Book1.title,"CProgramming"); strcpy(Book1.author,"NuhaAli"); strcpy(Book1.subject,"CProgrammingTutorial"); Book1.book_id=6495407; /*book2 specification*/ strcpy(Book2.title,"TelecomBilling"); strcpy(Book2.author,"ZaraAli"); strcpy(Book2.subject,"TelecomBillingTutorial"); Book2.book_id=6495700; /* printBook1info*/
34. printf("Book 1title: %sn",Book1.title); printf("Book 1author:%sn",Book1.author); printf("Book 1subject:%sn",Book1.subject); printf("Book 1book_id:%dn",Book1.book_id); /*printBook2info*/ printf("Book 2title: %sn",Book2.title); printf("Book 2author:%sn",Book2.author); printf("Book 2subject:%sn",Book2.subject); printf("Book 2book_id:%dn",Book2.book_id); return0; } OUTPUT : Book 1title:C Programming Book 1author:NuhaAli Book 1subject:CProgrammingTutorial Book 1book_id: 6495407 Book 2title:Telecom Billing Book 2author:ZaraAli Book 2subject:TelecomBilling Tutorial Book 2book_id: 6495700 Structures as Function Arguments: You can pass a structure as a function argument in thesameway as you pass any other variableor pointer. #include<stdio.h> #include<string.h> struct Books { char title[50]; char author[50]; char subject[100];
35. int book_id; }; /*function declaration */ void printBook( struct Books book ); int main( ) { struct Books Book1; /*DeclareBook1 of typeBook */ struct Books Book2; /*DeclareBook2 of typeBook */ /*book 1 specification */ strcpy( Book1.title, "C Programming"); strcpy( Book1.author, "Nuha Ali"); strcpy( Book1.subject, "C Programming Tutorial"); Book1.book_id = 6495407; /*book 2 specification */ strcpy( Book2.title, "TelecomBilling"); strcpy( Book2.author, "Zara Ali"); strcpy( Book2.subject, "TelecomBilling Tutorial"); Book2.book_id = 6495700; /*print Book1 info*/ printBook( Book1 ); /*Print Book2 info*/ printBook( Book2 ); return 0; } void printBook( struct Books book ) { printf( "Book title: %sn", book.title); printf( "Book author : %sn", book.author); printf( "Book subject : %sn", book.subject); printf( "Book book_id : %dn", book.book_id); }
36. OUTPUT: Book title:CProgramming Book author:NuhaAli Book subject:CProgrammingTutorial Book book_id:6495407 Book title:TelecomBilling Book author:ZaraAli Book subject:TelecomBilling Tutorial Book book_id:6495700 Pointers to Structures : Youcandefinepointerstostructuresinthesamewayasyou definepointertoanyother variable– struct Books *struct_pointer; Now, youcanstoretheaddressof a structurevariableintheabovedefinedpointervariable. Tofindtheaddressof a structurevariable,placethe'&';operatorbeforethestructure'sname as follows – struct_pointer=&Book1; Toaccessthemembersof a structureusingapointertothatstructure,youmustusethe→ operatoras follows – struct_pointer->title; Program: #include<stdio.h> #include<string.h> structBooks { char title[50]; char author[50]; char subject[100]; int book_id; };
37. /*functiondeclaration*/ void printBook(structBooks*book); intmain() { structBooksBook1; /* Declare Book1of typeBook */ structBooksBook2; /*DeclareBook2 of typeBook */ /* book1specification*/ strcpy(Book1.title,"CProgramming"); strcpy(Book1.author,"AshutoshSrivastava"); strcpy(Book1.subject,"CProgrammingLanguage"); Book1.book_id=101; /*book2 specification*/ strcpy(Book2.title,"TelecomBilling"); strcpy(Book2.author,"AshuSrivastava"); strcpy(Book2.subject,"TelecomBilling"); Book2.book_id=102; /*printBook1infobypassingaddressofBook1 */ printBook(&Book1); /*printBook2infobypassingaddressof Book2*/ printBook(&Book2); return0; } void printBook(structBooks*book) { printf("Book title:%sn",book->title); printf("Book author:%sn",book->author); printf("Book subject:%sn",book->subject); printf("Book book_id:%dn",book->book_id); } OUTPUT: Book title:CProgramming Book author:AshutoshSrivastava Book subject:CProgrammingLanguage
38. Book book_id:101 Book title:Telecom Billing Book author:AshuSrivastava Book subject:TelecomBilling Book book_id:102 Unions Aunionisa specialdatatypeavailablein Cthatallowstostoredifferent datatypesin the samememory location.Youcandefineaunionwithmanymembers,butonlyonemember cancontainavalueatanygiventime. Unionsprovideanefficientwayof usingthesame memory locationformultiple-purpose. Defining a Union : Todefineaunion,youmustusetheunionstatementinthesameway asyou didwhile definingastructure.Theunionstatementdefinesanewdatatypewithmorethanone member foryourprogram.Theformatof theunionstatementisasfollows – union[uniontag] { member definition; member definition; ... member definition; } [oneor moreunionvariables]; Program: #include<stdio.h> #include<string.h> unionData { inti; float f; charstr[20];
39. }; int main( ) { unionDatadata; printf("Memory sizeoccupiedbydata: %dn",sizeof(data)); return0; } OUTPUT:Memory sizeoccupiedbydata: 20 AccessingUnionMembers: Toaccessanymemberof a union,weusethememberaccessoperator(.). Themember accessoperatoris codedas aperiod between theunionvariablenameandtheunion member thatwewishtoaccess.Youwould usethekeyworduniontodefinevariables of uniontype. Program: #include<stdio.h> #include<string.h> unionData { inti; float f; charstr[20]; }; intmain() { unionDatadata; data.i= 10; data.f=220.5; strcpy(data.str,"CProgramming"); printf("data.i:%dn",data.i); printf("data.f:%fn",data.f); printf("data.str:%sn",data.str); return0;
40. } OUTPUT: data.i: 1917853763 data.f:4122360580327794860452759994368.000000 data.str:CProgramming Bit Fields SupposeyourCprogramcontainsanumberofTRUE/FALSE variablesgroupedina structurecalledstatus,asfollows– struct { unsignedintwidthValidated; unsignedintheightValidated; } status; Program: #include<stdio.h> #include<string.h> /*definesimple structure*/ struct { unsignedintwidthValidated; unsignedintheightValidated; } status1; /*definea structurewithbitfields*/ struct { unsignedintwidthValidated:1;
41. unsignedintheightValidated:1; } status2; intmain() { printf("Memorysizeoccupiedbystatus1:%dn",sizeof(status1)); printf("Memorysizeoccupiedbystatus2:%dn",sizeof(status2)); return0; } OUTPUT:Memory sizeoccupiedbystatus1:8 Memory sizeoccupiedbystatus2:4 Bit Field Declaration: struct { type[member_name]:width; }; Sr.No . Element & Description 1 Type An integer type that determines how a bit-field's value is interpreted. The type may beint, signed int, or unsigned int. 2 member_name Thenameof thebit-field. 3 Width Thenumberofbits inthebit-field.Thewidthmustbeless than or equaltothebit width of thespecified type.
42. struct { unsignedintage:3; } Age; Program: #include<stdio.h> #include<string.h> struct { unsignedintage:3; } Age; intmain() { Age.age=4; printf("Sizeof(Age) : %dn",sizeof(Age)); printf("Age.age: %dn",Age.age); Age.age=7; printf("Age.age: %dn",Age.age); Age.age=8; printf("Age.age: %dn",Age.age); return0; } OUTPUT: Sizeof( Age) : 4 Age.age: 4 Age.age: 7 Age.age: 0 typedef
43. TheC programminglanguageprovidesakeywordcalled typedef,whichyoucanuseto giveatypeanewname. typedef unsignedcharBYTE; Program: #include<stdio.h> #include<string.h> typedefstructBooks { chartitle[50]; charauthor[50]; charsubject[100]; intbook_id; } Book; intmain() { Book book; strcpy(book.title,"CProgramming"); strcpy(book.author,"AshutoshSrivastava"); strcpy(book.subject,"CProgrammingLanguage"); book.book_id=101; printf("Book title: %sn",book.title); printf("Book author:%sn",book.author); printf("Book subject:%sn",book.subject); printf("Book book_id:%dn",book.book_id); return0; } OUTPUT: Book title: CProgramming Book author:AshutoshSrivastava Book subject:CProgrammingLanguage Book book_id:101
44. typedef vs #define: #defineis a C-directive which is also used to define the aliases for various data types similar totypedef but with thefollowing differences −  typedef is limited to giving symbolic names to types only where as #definecan be used todefinealias for values as well, q., you can define1 as ONE etc.  typedef interpretationisperformedby thecompiler whereas #definestatements are processed by thepre-processor. Program: #include<stdio.h> #defineTRUE 1 OUTPUT: Valueof TRUE : 1 #defineFALSE 0 Value of FALSE : 0 int main( ) { printf( "Valueof TRUE : %dn", TRUE); printf( "Valueof FALSE : %dn", FALSE); return 0; } QUESTION 1: StoreInformation (name, rolland marks) of a Student Using Structure.
45. 2: Add TwoDistances (in inch-feet) SystemUsing Structures.
46. 3: Add TwoComplex Numbers by Passing Structuretoa Function.
47. 4: CalculateDifferenceBetween TwoTimePeriod.
48. 5: StoreInformation of 10 Students Using Structure.
49. Session-8 Strings Stringsareactuallyone-dimensionalarrayofcharactersterminatedbyanullcharacter'0'. Thusanull-terminatedstringcontainsthecharactersthatcomprisethestringfollowedby a null. chargreeting[6]={'H','e','l', 'l', 'o', '0'}; chargreeting[]="Hello"; Program: #include<stdio.h> intmain() { chargreeting[6]={'H','e','l', 'l', 'o', '0'}; printf("Greetingmessage:%sn",greeting); return0; } OUTPUT: Greeting:Hello
50. Sr.No. Function & Purpose 1 strcpy(s1, s2); Copies string s2 into string s1. 2 strcat(s1, s2); Concatenates string s2 onto the end of string s1. 3 strlen(s1); Returns the length of string s1. 4 strcmp(s1, s2); Returns 0 if s1 and s2 are the same; less than 0 if s1<s2; greater than 0 if s1>s2. 5 strchr(s1, ch); Returns a pointer to the first occurrence of character ch in string s1. 6 strstr(s1, s2); Returns a pointer to the first occurrence of string s2 in string s1. Strcpy():TheC libraryfunctionchar*strcpy(char*dest,constchar*src)copiesthestring pointedto, bysrctodest. Declaration: char*strcpy(char*dest,constchar*src) Parameters:  dest − Thisis thepointertothedestinationarraywherethecontentistobecopied.  src − This is thestring tobecopied. Return Value : Thisreturnsapointertothedestinationstringdest. Program: #include<stdio.h>
51. #include<string.h> intmain() { charsrc[40]; chardest[100]; memset(dest, '0',sizeof(dest)); strcpy(src,"ThisisC.com"); strcpy(dest,src); printf("Finalcopied string:%sn",dest); return(0); } OUTPUT:Finalcopied string:ThisisC.com Strcat():TheC libraryfunctionchar*strcat(char*dest,constchar*src)appendsthe stringpointedtobysrctotheend of thestringpointedtobydest. Declaration: char*strcat(char*dest,constchar*src) Parameters:  dest − This is pointer tothedestination array, which should contain a C string, and should belargeenough tocontain theconcatenated resulting string.  src −This is thestring tobeappended. This should not overlap thedestination. Return Value: Thisfunctionreturnsapointertotheresultingstringdest. Program: #include<stdio.h> #include<string.h> intmain() { charsrc[50],dest[50]; strcpy(src, "Thisissource");
52. strcpy(dest,"Thisisdestination"); strcat(dest,src); printf("Finaldestinationstring:|%s|",dest); return(0); } OUTPUT:Finaldestinationstring:|ThisisdestinationThisissource| strlen():TheC libraryfunctionsize_tstrlen(constchar*str)computesthelengthofthe stringstrupto,butnotincludingtheterminatingnullcharacter. Declaration: size_tstrlen(constchar*str) Parameters : 1:str−Thisis thestringwhoselengthistobefound. Return Value : Thisfunctionreturnsthelengthofstring. Program : #include<stdio.h> #include<string.h> intmain() { charstr[50]; intlen; strcpy(str,"Thisisc.com"); len= strlen(str); printf("Lengthof|%s|is|%d|n",str,len); return(0);} OUTPUT :Lengthof|Thisisc.com|is |26|
53. Strcmp():The Clibraryfunctionintstrcmp(constchar*str1,constchar*str2)compares thestringpointedto,bystr1tothestringpointedtobystr2. Declaration: intstrcmp(constchar*str1,constchar*str2) Parameters:  str1 −This is thefirst string tobecompared.  str2 −This is thesecond string tobecompared. Return Value: This function return values that are as follows −  if Return value< 0 then it indicates str1 is less than str2.  if Return value> 0 then it indicates str2 is less than str1.  if Return value= 0 then it indicates str1 is equaltostr2. Program: #include<stdio.h> #include<string.h> int main () { char str1[15]; char str2[15]; int ret; strcpy(str1, "abcdef"); strcpy(str2, "ABCDEF"); ret = strcmp(str1, str2); if(ret < 0) { printf("str1 is less than str2"); } elseif(ret > 0)
54. { printf("str2 is less than str1"); } else { printf("str1 is equaltostr2"); } return(0); } OUTPUT :str2isless thanstr1 strchr(): TheClibraryfunctionchar*strchr(constchar*str,intc)searchesforthefirst occurrenceofthecharacterc(anunsignedchar)inthestringpointedtobythe argumentstr. Declaration: char*strchr(constchar*str,intc) Parameters  str −This is theC string tobescanned.  c −This is thecharacter tobesearched in str. Return Value : Thisreturnsapointertothefirstoccurrenceofthecharactercinthestringstr,orNULLif thecharacterisnotfound. Program: #include<stdio.h> #include<string.h>
55. intmain() { constcharstr[]="http://www.ashutoshsrivasatava.com"; constcharch='.'; char*ret; ret= strchr(str,ch); printf("Stringafter|%c|is-|%s|n",ch,ret); return(0); } OUTPUT :Stringafter|.|is-|.ashutoshsrivasatava.com| strstr():TheClibraryfunctionchar*strstr(constchar*haystack,constchar *needle) functionfindsthefirstoccurrenceofthesubstringneedleinthestringhaystack. Theterminating'0'charactersarenotcompared. Declaration: char *strstr(const char *haystack, const char *needle) Parameters:  haystack −This is themain C string tobescanned.  needle−This is thesmallstring tobesearched with-in haystack string. Return Value: Thisfunctionreturnsapointertothefirstoccurrenceinhaystackofanyoftheentire sequence of characters specified in needle, or a null pointer if the sequence is not present in haystack.
56. Program: #include<stdio.h> #include<string.h> intmain() { constcharhaystack[20]="Ashutosh"; constcharneedle[10]="Point"; char*ret; ret= strstr(haystack,needle); printf("Thesubstringis:%sn",ret); return(0); } OUTPUT: Thesubstringis:Point QUESTION 1: WAP toCheckifagivenStringisPalindrome.
57. 2:WAP toCheckifaStringisaPalindromewithoutusingtheBuilt-inFunction.
58. 3:WAP toFindtheLargest&Smallest Wordin aString.
59. Session-9 Pointers Pointers in“c”languageisa variablethatstores/pointstheaddressofanothervariable.A pointerin“C” is usedtoallocatedynamicallyi.e. atruntime,thepointervariablemightbe belongingtoanyof thedatatypesuchasint,float,char,double,short etc. Program: #include<conio.h> #include<stdio.h> void main() { int var1; charvar2[20]; printf(“Address:%xn”,&var1); printf(“Address:%xn”,&var2); getch(); } OUTPUT : Address : bff5a400 Address :bff5a3f6
60. What arePointers? Apointeris a variablewhosevalueis theaddressof anothervariable,i.e., directaddressof thememory location.Likeanyvariableorconstant,youmustdeclareapointerbeforeusing ittostoreanyvariableaddress.Thegeneralformof a pointervariabledeclarationis – type*var-name; Example: int *ip; /*pointertoaninteger*/ double*dp; /*pointertoa double*/ float *fp; /*pointertoa float*/ char *ch /* pointertoa character*/ How to UsePointers? #include<stdio.h> intmain() { int var=20; /*actualvariabledeclaration*/ int *ip; /* pointervariabledeclaration*/ ip =&var; /*storeaddressof varinpointervariable*/ printf("Addressof varvariable:%xn",&var ); /* addressstoredinpointervariable*/ printf("Addressstoredinip variable:%xn",ip ); /*accessthevalueusingthepointer*/ printf("Valueof*ip variable: %dn",*ip); return0; } OUTPUT : Address ofvar variable:bffd8b3c Address storedinip variable:bffd8b3c Valueof *ip variable: 20 NULL Pointers: Itis always agood practicetoassignaNULLvaluetoapointervariableincaseyoudonot haveanexactaddresstobeassigned.Thisis doneatthetimeof variabledeclaration.A pointerthatisassignedNULLis calleda nullpointer.
61. Program: #include<stdio.h> intmain() { int *ptr=NULL; printf("Thevalueof ptris: %xn",ptr ); return0; } OUTPUT : Thevalueof ptris 0 Pointers inDetail : Sr.No. Concept & Description 1 Pointerarithmetic There are four arithmetic operators that can be used in pointers: ++, --, +, - 2 Array of pointers You can define arrays to hold a number of pointers. 3 Pointerto pointer C allows you to have pointer on a pointer and so on. 4 Passing pointersto functionsin C Passing an argument by reference or by address enable the passed argument to be changed in the calling function by the called function. 5 Return pointerfrom functionsin C “C” allows a function to return a pointer to the local variable, static variable and dynamically allocated memory as well.
62. Pointer arithmetic A pointer in c is an address, which is a numeric value. Therefore, you can performarithmetic operations on a pointer just as you can on a numeric value. Thereare four arithmetic operators that can beused on pointers: ++, --, +, and - ptr++ Incrementing a Pointer Program: #include<stdio.h> const int MAX = 3; int main () { int var[] = {10, 100, 200}; int i, *ptr; /* let us have array address in pointer */ ptr = var; for ( i = 0; i < MAX; i++) { printf("Address of var[%d] = %xn", i, ptr ); printf("Valueof var[%d] = %dn", i, *ptr ); /* move to the next location */ ptr++; } return 0; } OUTPUT : Address of var[0] = bf882b30 Valueof var[0] = 10 Address of var[1] = bf882b34 Valueof var[1] = 100
63. Address of var[2] = bf882b38 Valueof var[2] = 200 Decrementing a Pointer Program: #include<stdio.h> const int MAX = 3; int main () { int var[] = {10, 100, 200}; int i, *ptr; /* let us havearray address in pointer */ ptr = &var[MAX-1]; for ( i = MAX; i > 0; i--) { printf("Address of var[%d] = %xn", i-1, ptr ); printf("Valueof var[%d] = %dn", i-1, *ptr ); /* move to theprevious location */ ptr--; } return 0; } OUTPUT: Address of var[2] = bfedbcd8 Valueof var[2] = 200 Address of var[1] = bfedbcd4 Valueof var[1] = 100 Address of var[0] = bfedbcd0 Valueof var[0] = 10 Pointer Comparisons Program:
64. #include<stdio.h> constintMAX=3; intmain() { int var[]={10,100,200}; int i,*ptr; /*let ushaveaddressof thefirstelementin pointer*/ ptr=var; i=0; while( ptr<=&var[MAX-1]) { printf("Addressof var[%d]=%xn",i,ptr); printf("Valueofvar[%d]=%dn",i,*ptr ); /*point totheprevious location*/ ptr++; i++; } return0; } OUTPUT: Address ofvar[0]= bfdbcb20 Valueof var[0]=10 Address ofvar[1]= bfdbcb24 Valueof var[1]=100 Address ofvar[2]= bfdbcb28 Valueof var[2]=200 Arrayofpointers Program :#include<stdio.h> const int MAX = 3; int main () {
65. int var[] = {10, 100, 200}; int i; for (i = 0; i < MAX; i++) { printf("Valueof var[%d] = %dn", i, var[i] ); } return 0; } OUTPUT: Valueof var[0] = 10 Valueof var[1] = 100 Valueof var[2] = 200 Program: #include<stdio.h> const int MAX = 4; int main () { char *names[] = { "Zara Ali", "Hina Ali", "Nuha Ali", "Sara Ali" }; int i = 0; for ( i = 0; i < MAX; i++) { printf("Valueof names[%d] = %sn", i, names[i] ); }
66. return 0; } OUTPUT : Valueof names[0] = Zara Ali Valueof names[1] = Hina Ali Valueof names[2] = Nuha Ali Valueof names[3] = Sara Ali Pointer to Pointer A pointer to a pointer is a form of multipleindirections, or a chain of pointers. Normally, a pointer contains theaddress of a variable. When we define a pointer to a pointer, the first pointer contains theaddress of thesecond pointer, which points to the location that containstheactualvalueas shown below. int **var; Program : #include<stdio.h> int main () { int var; int *ptr; int **pptr; var = 3000; /* takethe address of var */ ptr = &var;
67. /* taketheaddress of ptr using address of operator & */ pptr = &ptr; /* takethe value using pptr */ printf("Valueof var = %dn", var ); printf("Valueavailable at *ptr = %dn", *ptr ); printf("Valueavailableat **pptr = %dn", **pptr); return 0; } OUTPUT : Valueof var = 3000 Valueavailable at *ptr = 3000 Valueavailable at **pptr = 3000 Passingpointers to functions C programming allows passing a pointer to a function. To do so, simply declare the function parameter as a pointer type.Following is a simple example where we pass an unsigned long pointer toa function and change the value inside the function which reflects back in the calling function − Program: #include<stdio.h> #include<time.h> void getSeconds(unsigned long *par); int main () { unsigned long sec; getSeconds(&sec ); /* print theactualvalue*/ printf("Number of seconds: %ldn", sec ); return 0; } void getSeconds(unsigned long *par)
68. { /* get the currentnumberof seconds */ *par = time( NULL ); return; } OUTPUT: Number of seconds :1294450468 Program : #include<stdio.h> /* functiondeclaration*/ double getAverage(int*arr, int size); int main () { /* an int array with 5 elements */ int balance[5] = {1000, 2, 3, 17, 50}; doubleavg; /* pass pointer to the array as an argument */ avg = getAverage( balance, 5 ) ; /* output thereturned value */ printf("Averagevalueis: %fn", avg ); return 0; } double getAverage(int*arr, int size) { int i, sum = 0; doubleavg;
69. for (i = 0; i < size; ++i) { sum += arr[i]; } avg = (double)sum/ size; return avg; } OUTPUT: Average value is: 214.40000 Return pointer from functions C also allows to return a pointer from a function. Todo so, you would have to declarea functionreturning a pointer as in thefollowing example – int * myFunction() { } Second point to remember is that, it is not a good idea to return theaddress of a local variableoutsidethe function,so you would have to define thelocal variable as static variable. Program : #include<stdio.h> #include<time.h> /* functiontogenerateand return randomnumbers.*/ int * getRandom( ) { static int r[10]; int i; /* set the seed */
70. srand( (unsigned)time( NULL ) ); for ( i = 0; i < 10; ++i) { r[i] = rand(); printf("%dn", r[i] ); } return r; } /* main function tocallabove defined function */ int main () { /* a pointer to an int */ int *p; int i; p = getRandom(); for ( i = 0; i < 10; i++ ) { printf("*(p + [%d]) : %dn", i, *(p + i) ); } return 0; }
71. QUESTION 1: Program to print a string using pointer.
73. 3: Program to print size of different types of pointer variables.
74. Session–10 Filesand I/O A file represents a sequenceof bytes, regardless of it being a text file or a binary file. C programminglanguageprovides access on high level functions as well as low level (OS level) calls to handlefile on your storagedevices. This chapter will takeyou throughtheimportant calls for file management. Types ofFiles: When dealing with files, thereare two types of files you should knowabout: 1. Text files 2. Binary files 1.Text files: Text files are the normal.txt files that you can easily createusing Notepad or any simple text editors. When you open those files, you'll see all the contents withinthefile as plain text. You can easily edit or delete the contents. They takeminimumeffort to maintain, areeasily readable, and provide least security and takes bigger storagespace.
75. Opening Files: You can use the fopen( ) functiontocreatea new file or to open an existing file. This call will initializean object of the type FILE, which contains allthe information necessary tocontrolthestream. Theprototypeof this function callis as follows – FILE *fopen( const char * filename, const char * mode ); Sr.No. Mode & Description 1 R Opens an existing text file for reading purpose. 2 W Opens a text file for writing. If it does not exist, then a new file is created. Here your programwill start writing content fromthe beginningof thefile. 3 A Opens a text file for writing in appending mode. If it does not exist, then a new file is created. Hereyour programwill start appending contentin theexisting file content. 4 r+ Opens a text file for both reading and writing. 5 w+ Opens a text file for both reading and writing. It first truncates the file to zerolength if it exists, otherwisecreates a file if it does not exist. 6 a+
76. Opens a text file for both reading and writing. It creates thefile if it does not exist. Thereading will start from thebeginning but writing can only be appended. If you are going to handlebinary files, then you will use following access modes instead of the above mentioned ones – "rb", "wb", "ab", "rb+", "r+b", "wb+", "w+b", "ab+", "a+b" ClosingaFile: To close a file, use the fclose( ) function. Theprototypeof this functionis − int fclose( FILE *fp ); The fclose(-) function returnszeroon success, or EOF if thereis an error in closing thefile. This function actually flushes any data stillpending in the buffer to the file, closes the file, and releases any memory used for the file. The EOF is a constant defined in theheader file stdio.h. Writinga File: Following is the simplest function towrite individualcharacters toa stream − int fputc( int c, FILE *fp ); The function fputc() writes thecharactervalueof the argumentc to the output streamreferenced by fp. It returns thewritten characterwritten on success otherwiseEOF if thereis an error. You can usethe following functions towritea null-terminated string toa stream – int fputs( const char *s, FILE *fp ); The function fputs() writes thestring s to the output streamreferenced by fp. It returns a non-negativevalueon success, otherwise EOF is returned in caseof any error. You can use int fprintf(FILE *fp,constchar *format, ...)function as well to write a string intoa file. Program: #include<stdio.h>