Loops
are used to execute a set of statements repeatedly until a particular condition
is satisfied
The
basic purpose of loop is to execute set of statements until condition becomes
false and same code repeated again and again.
Advantage
It
is used to reduce length of Code
It takes less memory space.
Types
of Loops
There are three types of loop
available in C++ programming language.
·
while
loop
·
for
loop
·
do-while
While loop
While loop
In while loop
First check the condition if condition is true then the control goes inside the
loop body and print the output , It will
repeated again and again until condition becomes false. If condition becomes
false control goes outside the body and loop is terminated
Syntax:
assignment;
while(condition){
Statements;
………….
Increment/decrement
(++,--)
}
Example:
#include
<iostream.h>
#include<conio.h>
void main ()
{
int i=1;
clrscr();
while(i<=5)
{
cout<<i <<endl;
i++;
}
getch();
}
Output:
1
2
3
4
5
Note: If while loop condition never false then loop becomes
infinite loop
do-while
First print output then checks the condition. Since condition is checked later, the body statements will execute at least once
Syntax:
do-while
First print output then checks the condition. Since condition is checked later, the body statements will execute at least once
Syntax:
assignment;
do
{
Statements;
………….
Increment/decrement(++,--)
}
while(condition);
Example:
#include<iostream.h>
#include<conio.h>
void main()
{
int i;
clrscr();
i=1;
do
{
cout<<endl<<i;
i++;
}
while(i<=5);
getch();
}
Output:
1
2
3
4
5
For loop
for loop is used to iterate a program several times
and execute the code repeatedly.
We can initialize variable, check condition
and increment/decrement value.
Syntax:
for(initialization; condition; increment/decrement)
{
//Statement
}
Example:
#include<iostream.h>
#include<conio.h>
void main()
{
int i;
clrscr();
for(i=1;i<=5;i++)
{
cout<<endl<<i;
}
getch();
}
Output:
1
2
3
4
5
Break
break is used to break loop or switch
statement.
Syntax:
statement;
break;
Example:
#include
<iostream.h>
#include <conio.h>
void main()
{
for (int i = 1; i <= 5; i++)
{
if (i == 4)
{
break;
}
cout<<i<<"\n";
}
getch();
}
Output:
1
2
3
Continue
continue statement is used to continue loop.
Syntax:
Statement;
continue;
Example:
#include
<iostream.h>
#include <conio.h>
void main()
{
for(int i=1;i<=5;i++){
if(i==3){
continue;
}
cout<<i<<endl;
}
getch();
}
Output:
1
2
4
5
Comments
Comments are not executed by compiler.
Comments are used to highlight the statements.
You can explain code, variable, method,
object, property or class but not execute the code.
There are two types of comments in C++.
- Single Line comment (//)
- Multi Line comment (/∗ ..... ∗/).
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