Switch case and looping statement

Final Requirement for Fundamentals of
Programming

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• A program is a sequence of instruction written to
perform a specified task with a computer. A computer
requires programs to function, typically executing the
program's instructions in central processor. The
program has an executable form that the computer can
use directly to execute the instructions. The same
program in its human-readable source code form, from
which executable programs are derived (e.g.,
compiled), enables a programmer to study and develop
its algorithms.


• Computer source code is often written
by computer programmers. Source code is written
in a programming language that usually follows
one of two main paradigms: imperative
programming or declarative programming. Source
code may be converted into an executable
file (sometimes called an executable program or a
binary) by a compiler and later executed by a
central processing unit.


A computer programmer is a person who
writes computer software. The term computer
programmer can refer to a specialist in one area
of computer programming or to a generalist who writes
code for many kinds of software. One who practices or
professes a formal approach to programming may also
be known as a programmer analyst.


Programmers are people who design the program
of events that turns input data into output data. It
has been proved that such a program of events can
be designed using a structure composed of
sequences, iterations and selections. Code is
merely the way that the program is described.


Programming is the iterative process of writing
or editing source code. Editing source code involves testing,
analyzing, and refining, and sometimes coordinating with
other programmers on a jointly developed program. A
person who practices this skill is referred to as a
computer programmer, software developer or coder. The
sometimes lengthy process of computer programming is
usually referred to as software development. The
term software engineering is becoming popular as the
process is seen as an engineering discipline.


Programming is instructing a computer to do
something for you with the help of a programming
language. The role of a programming language can be
described in two ways:
1. Technical: It is a means for instructing a Computer to
perform Tasks
2. Conceptual: It is a framework within which we
organize our ideas about things and processes.


A programming language should both provide means to
describe primitive data and procedures and means to
combine and abstract those into more complex ones.

The distinction between data and procedures is not that
clear cut. In many programming languages, procedures can
be passed as data (to be applied to ``real'' data) and
sometimes processed like ``ordinary'' data. Conversely
``ordinary'' data can be turned into procedures by an
evaluation mechanism


In practicing programming one must know the basic
program a programmer use. Dev C++ can help us on
computing grades, making test questionnaires and
many more things a teacher and a student can do.
Programming is a an act of formulating a program for a
definite course of action; "the planning was more fun
than the trip itself“.


• C++ is a statically typed, free-form, multi-
paradigm, compiled, general-purpose programming language. It
is regarded as an intermediate-level language, as it comprises a
combination of both high-level and low-level language features.

• C++ is one of the most popular programming languages and is
implemented on a wide variety of hardware and operating
system platforms.

• C++ has greatly influenced many other popular programming
languages, most notably C# and Java. Other successful languages
such as Objective-C use a very different syntax and approach to
adding classes to C.


C/C++ has a built-in multiple-branch selection
statement, called switch, which successively tests the
value of an expression against a list of integer
or character constants. When a match is found, the
statements associated with that constant are executed.


Programs have a need to do different things depending
on user input or based on the flow of the program itself. If
statements can do this work, but sometimes it is much
easier to use other forms that might work more easily for
menu items or what to do with different rolls of a die. The
switch statement can be very helpful in handling multiple
choices in programming.

This program will ask the user to select a number from
a predetermined set of numbers. Then the program will
print different things on the screen depending on which
number the user chose

In programming,a switch, case, select or inspect sta
tement is a type of selection control mechanism that exists in
most imperative programming languages such
as Pascal, Ada, C/C++,C#, Java, and so on. It is also included
in several other types of languages. Its purpose is to allow the
value of a variable or expression to control the flow of
program execution via a multi way branch(or "goto", one of
several labels). The main reasons for using a switch include
improving clarity, by reducing otherwise repetitive coding,
and (if the heuristics permit) also offering the potential for
faster execution through easier compiler optimization in
many cases.

switch (expression)
{
case constant1
:statement sequence
break;
case constant2
:statement sequence
break;
case constant3
:statement sequence
break;

default
statement sequence
}


The expression must evaluate to a character or integer
value. Floating-point expressions, for example, are not
allowed. The value of expression is tested, in order,
against the values of the constants specified in the case
statements. When a match is found, the statement
sequence associated with that case is executed until the
break statement or the end of the switch statement is
reached. The default statement is executed if no matches
are found. The default is optional and, if it is not present,
no action takes place if all matches fail.


• The switch differs from the if in that switch can only
test for equality, whereas if can evaluate any type of
relational or logical expression.
• No two case constants in the same switch can have
identical values. Of course, a switch statement
enclosed by an outer switch may have
case constants that are the same.
• If character constants are used in the switch
statement, they are automatically converted to integers


In programming switch case statement body consists a
series of case labels and an optional default label. No
two constant expressions in case statements can
evaluate to the same value.


The default label can appear only once. The labeled
statements are not syntactic requirements, but
the switch statement is meaningless without them. The
default statement need not come at the end; it can appear
anywhere in the body of the switch statement. A case or
default label can only appear inside a switch statement.


The constant-expression in each case label is
converted to the type of expression and compared
with expression for equality. Control passes to the
statement whose case constant-expression matches the
value of expression. If a matching expression is
found, control is not impeded by
subsequent case or default labels. The ”break ”statement
is used to stop execution and transfer control to the
statement after the switch statement. Without
a break statement, every statement from the matched
case label to the end of the switch, including
the default, is executed.


// switch_statement1.cpp
#include <stdio.h>
int main()
{ char *buffer = "Any character stream";
int capa, lettera, nota;
char c;
capa = lettera = nota = 0;
while ( c = *buffer++ ) // Walks buffer until NULL
{
switch ( c )
{
case 'A':
capa++;
break;
case 'a':
lettera++;
break;
default:
nota++;
}
}
printf_s( "nUppercase a: %dnLowercase a: %dnTotal: %dn",
capa, lettera, (capa + lettera + nota) );
}


On the example given , capa is incremented if c is an
uppercase A. The break statement after capa++ terminates
execution of the switch statement body and control passes
to the while loop. Without the break statement, letter
a and nota would also be incremented. A similar purpose is
served by the break statement for case 'a'. If c is a
lowercase a, letter a is incremented and
the break statement terminates the switch statement body.
If c is not an a or A, the default statement is executed.


In the series of the Programming language a loop statements
have an optional LABEL in their formal syntax. (You can put a
label on any statement, but it has a special meaning to a loop.) If
present, the label consists of an identifier followed by a colon. It's
customary to make the label uppercase to avoid potential
confusion with reserved words, and so it stands out better. And
although Perl won't get confused if you use a label that already
has a meaning like if or open, your readers might.


The ”while” statement in programming repeatedly executes the
block as long as EXPR is true. If the word while is replaced by the
word until, the sense of the test is reversed; that is, it executes
the block only as long as EXPR remains false. The conditional is
still tested before the first iteration, though.


The while or until statement can have an optional extra
block: the continue block. This block is executed every
time the block is continued, either by falling off the
end of the first block or by an explicit next (a loop-
control operator that goes to the next iteration). The
“continue ”block is not heavily used in practice, but it's
in here so we can define the for loop rigorously in the
next section


while (my $line = <STDIN>) {

$line = lc $line;

}

continue {

print $line; # still visible
}
# $line now out of scope here

Here the scope of $line extends from its declaration in the control expression throughout
the rest of the loop construct, including the continue block, but not beyond. If you want
the scope to extend further, declare the variable before the loop.


The ”for ” loop has three semicolon-separated
expressions within its parentheses. These expressions
function respectively as the initialization, the
condition, and the re-initialization expressions of the
loop. All three expressions are optional (but not the
semicolons); if omitted, the condition is always true


LABEL:
for (my $i = 1; $i <= 10; $i++) {
...
}
{
my $i = 1;
LABEL:
while ($i <= 10) {
...
}
continue {
$i++;
}
}

In programming a kind of “for” statement like this we ca see that the scope of the ”my” is
limited thus , the three-part for loop can be defined in terms of the
corresponding while loop.


A do-while loop in programming executes one or
more times, depending on the value of the termination
expression. The do-while statement can also
terminate when a break, go to, or return statement is
executed within the statement body.


// do_while_statement.cpp
#include <stdio.h>
int main()
{
int i = 0;
do
{
printf_s("n%d",i++);
} while (i < 3);
}

If expression is false, the do-while statement terminates and control passes to
the next statement in the program. If expression is true (nonzero), the process
is repeated, beginning with step 1.


Iteration statements cause statements (or
compound statements) to be executed zero or more times,
subject to some loop-termination criteria. When these
statements are compound statements, they are executed in
order, except when either the break statement or
the continue statement is encountered.
C++ program provides four iteration statements —
while, do, for, and range-based for. Each of these iterates
until its termination on the programming expression
evaluates to zero (false), or until loop termination is forced
with a break statement. The following table summarizes
these statements and their actions; each is discussed in
detail in the sections that follow.


#include <stdio.h>

int main() {
int color = 1;
printf("Please choose a color(1: red,2: green,3: blue):n");
scanf("%d", &color);

switch (color) {
case 1:
printf("you chose red colorn");
break;
case 2:
printf("you chose green colorn");
break;
case 3:
printf("you chose blue colorn");
break;
default:
printf("you did not choose any colorn");
}
return 0;
}


#include <iostream>

using namespace std;

void playgame()
{
cout << "Play game called";
}
void loadgame()
{
cout << "Load game called";
}
void playmultiplayer()
{
cout << "Play multiplayer game called";
}

int main()
{
int input;

cout<<"1. Play gamen";
cout<<"2. Load gamen";
cout<<"3. Play multiplayern";
cout<<"4. Exitn";
cout<<"Selection: ";
cin>> input;
switch ( input ) {
case 1: // Note the colon, not a semicolon
playgame();
break;
loadgame();
break;
playmultiplayer();
break;
cout<<"Thank you for playing!n";
break;
default: // Note the colon, not a semicolon
cout<<"Error, bad input, quittingn"; http://eglobiotraining.com
break;
}

#include <iostream.h>

int main()
{
unsigned short int day;
cout << "What's your favorite day of the week? ";
cin >> day;
switch (day)
{
case 1 : cout << "Sunday";
break;
case 2 : cout << "Monday";
break;
case 3 : cout << "Tuesday";
break;
case 4 : cout << "Wednesday";
break;
case 5 : cout << "Thursday";
break;
case 6 : cout << "Friday";
break;
case 7 : cout << "Saturday";
break;
default : cout << "Not an allowable day number";
break;

}
cout << "nn";
return 0;
} http://eglobiotraining.com

#include <iostream>
#include <math.h>
#include<stdio.h>

int main()
{
int number1;
int number2;
int number3;
int number4;
float Circle;
float Rectangle;
float Triangle;
int choice;
double pi;
float length;
float width;
float base;
float height;
float radius;

number1 = 1;
number2 = 2;
number3 = 3;
number4 = 4;
pi = 3.14159;
Circle = pi * radius * radius;
Rectangle = length * width;
Triangle = base * height * .5;


cout << "Geometry Calculator" << endl;

cout << "1. Calculate the Area of a Circle" << endl;
cout << "2. Calculate the Area of a Rectangle" << endl;
cout << "3. Calculate the Area of a Triangle" << endl;
cout << "4. Quit" << endl << endl;

cout << "Enter your choice (1-4):" << endl;
cin >> choice;

switch(choice)
{
case 1 : cout << "Enter the radius of the circle:" << endl;
cin >> radius;
case 2 : cout << "Enter the length of the rectangle:" << endl;
cin >> length;
cout << "Enter the width of the rectangle:" << endl;
cin >> width;
case 3 : cout << "Enter the height of the triangle:" << endl;
cin >> height;
case 4 : cout << "Goodbye!" << endl;
default: cout << "5 is not a valid entry." << endl;
}
return 0;
}


#include <stdio.h>
#include <iostream>

int main()
{
int nr = 0;
char ch = 0;

//This uses numbers
cout << "Type in number 1 or 2: ";
cin >> nr;

switch(nr)
{
case 1:
cout << "The number typed was 1!n";
break;

case 2:
cout << "The number typed was 2!n";
break;

default:
cout << "You didn't type in 1 or 2!n";
break;

}


//This uses lowercase characters only
cout << "nn Type in character a or b: ";
cin >> ch;

switch(ch)
{
case 'a':
cout << "You typed in an A!n";
break;

case 'b':
cout << "You typed in an B!n";
break;

default:
cout << "You didn't type in a or b!n";
break;
}

//This uses lowercase an uppercase characters
cout << "nnType in lowercase or uppercase a or b: ";
cin >> ch;

switch(ch)
{
case 'a': case 'A':
cout << "You typed in an A!n";
break;

case 'b': case 'B':
cout << "You typed in an B!n";
break;

default:
cout << "You didn't type in a or b!n";
break;
}

getchar(); // wait for a key to be pressed.

return 0;
}


#include <iostream>
#include <string>


int main(){

string choice = "y";

while ( choice == "y" ){

cout << "Say something about this" << endl;

cout << "Leave your comments." << endl;
cin >> choice;

}

cout << "You exited the loop" << endl;

}


#include <iostream>


int main(){

int a;

cout << "How long do you want this program to run? ";
cin >> a;

while (a){
cout << a << "n";
--a;
}

return 0;

}


int main()
{
int x = 0; /* Don't forget to declare variables */

while ( x < 16 ) { /* While x is less than 16*/
printf( "%dn", x );
x++; /* Update x so the condition can be met eventually */
}
getchar();
}


#include <stdio.h>

int main()
{
int x;

x = 0;
do {
/* "He who hesitates is lost.-Proverb" is printed at least one time
even though the condition is false */
printf( "He who hesitates is lost.-Proverb" );
} while ( x != 0 );
getchar();
}


#include <stdio.h>

int main()
{
int i, count;
printf("Enter the number of the item: ");
scanf("%d", &count, 1);
for(i = 1; i <= count; i = i + 1)
printf(" %d", i);
printf("n");
return 0;
}


Switch Statement:
• The first line contains the basic keyword,
usually switch, case or select, followed by an
expression which is often referred to as the control
expression or control variable of the switch statement.

• Subsequent lines define the actual cases (the
values) with corresponding sequences of statements
that should be executed when a match occurs.


Each alternative begins with the particular value, or
list of values (see below), that the control variable may
match and which will cause the control to go to the
corresponding sequence of statements. The value (or
list/range of values) is usually separated from the
corresponding statement sequence by a colon or an
implication arrow. In many programming languages, every
case must also be preceded by a keyword such
as case or when. An optional default case is typically also
allowed, specified by a default or else keyword; this is
executed when none of the other cases matches the control
expression.


• When the program starts the user is prompted
to insert a starting number for the countdown. Then
the while loop begins, if the value entered by the user
fulfills the condition n>0 (that n is greater than zero)
the block that follows the condition will be executed
and repeated while the condition (n>0) remains being
true.

• The easiest way to think of the loop in the
programming is when it reaches the brace at the end it
jumps back up to the beginning of the loop, which
checks the condition again and decides whether to
repeat the block another time, or stop and move to the
next statement after the block.


Submitted by:
Jenica H. Tubungbanua
BM10203


Switch case and looping statement

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