As a part of the course material of CSC 391- Data structure and algorithm. Review of previous concept of array, pointer and functions.

1. Practice codes for CSC- 391
ARRAY< FUNCTION< POINTERS
1. Passing pointer to array
#include <stdio.h>
#include <time.h>
void getSeconds(unsigned long *par);
int main ()
{
unsigned long sec;
getSeconds( &sec );
/* print the actual value */
printf("Number of seconds: %ldn", sec );
return 0;
}
void getSeconds(unsigned long *par)
{
/* get the current number of seconds */
*par = time( NULL );
return;
}
2. passing array to a function
#include <stdio.h>
#include <stdio.h>
double getAverage(int *arr, int size);
int main ()
{
int balance[5] = {1000, 2, 3, 17, 50};
double avg;
/* pass pointer to the array as an argument */
avg = getAverage( balance, 5 ) ;
/* output the returned value */
printf("Average value is: %fn", avg );

2. return 0;
}
double getAverage(int *arr, int size)
{
int i, sum = 0;
double avg;
for (i = 0; i < size; ++i)
{
sum += arr[i];
}
avg = (double)sum / size;
return avg;
}
// double getAverage(int arr[], int size)
{
int i;
double avg;
double sum;
for (i = 0; i < size; ++i)
{
sum += arr[i];
}
avg = sum / size;
return avg;
}
Some methods in string.h:
S.N. 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.
3. Using string methods:
#include <stdio.h>
#include <string.h>
int main ()
{
char str1[12] = "Hello";
char str2[12] = "World";

3. char str3[12];
int len ;
/* copy str1 into str3 */
strcpy(str3, str1);
printf("strcpy( str3, str1) : %sn", str3 );
/* concatenates str1 and str2 */
strcat( str1, str2);
printf("strcat( str1, str2): %sn", str1 );
/* total lenghth of str1 after concatenation */
len = strlen(str1);
printf("strlen(str1) : %dn", len );
return 0;
}
4. Returning pointer from a function
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
/* function to generate and retrun random numbers. */
int * getRandom( )
{
static int r[10];
int i;
for ( i = 0; i < 10; ++i)
{
r[i] = rand();
printf("%dn", r[i] );
}
return r;
}
/* main function to call above defined function */
int main ()
{
int *p;
int i;
p = getRandom();
for ( i = 0; i < 10; i++ )
{

4. printf("*(p + [%d]) : %dn", i, *(p + i) );
}
return 0;
}
Pattern Matching
#include<stdio.h>
#include<conio.h>
#include<string.h>
int main()
{
char T[100]="Pattern Matching Algorithm";
char P[20]="Pattern";
int r,s,i, k=0, max, index;
s=strlen(T);
r=strlen(P);
max= s-r;
while(k<=max)
{
for(i=0; i<r; i++)
{
if(P[i]!=T[k+i]) break;
}
if(i==R)
{
index=k;
break;
}
else k=k+1;
}
if(k>max) index=-1;
printf("T = %s", T);
printf("nP = %s", P);
if(index!=-1) printf("nn Index of P in T is %d", index);
else printf("n P does not occur in T");
getch();
return 0;
}