Loops

Types of Loops :

There are three types of loops.

1. For-Loop
2. While Loop
3. Do-While Loop

1. For Loop :

For loops are used when you have a block of code which you want to repeat a fixed number of times.

Loop controling concept

Syntax of For-Loop

for (initialization; condition; increment/decrement)

 {

 // you can perform your code here in a loop

 }

initialization:

Typically initializes a loop control variable. It's executed once at the beginning of the loop.

condition:

It's a boolean expression that determines whether the loop should continue or not. If it evaluates to true, the loop continues; otherwise, the loop terminates.

increment/decrement:

Modifies the loop control variable to bring the loop closer to the termination condition. It's executed after each iteration of the loop.

Check the examples below 👇

💻Example :

#include <stdio.h>

int main() {

    for(int i=0;i<=5; i++)
    {
        printf("\nHello ");
    }
    return 0;
}

Output :

Hello
Hello
Hello
Hello
Hello
Hello

Example :

#include <stdio.h>

int main() {

    int n;
    printf("Enter Number :");
    scanf("%d",&n);

    for(int i=1;i<=n; i++)
    {
        printf("\nHey ");
    }
    return 0;
}

Output :

Enter Number :5
Hey
Hey
Hey
Hey
Hey

Example :

#include <stdio.h>

int main() {

    int n;
    printf("Enter Number :");
    scanf("%d",&n);

    for(int i=1;i<=n; i++)
    {
        printf("\nXerox... %d",i);
    }
    return 0;
}

Output :

Enter Number :3
Xerox... 1
Xerox... 2
Xerox... 3

Example :

#include <stdio.h>

int main() {

    for(int i=5;i>=0; i--)
    {
        printf("\n%d",i);
    }
    return 0;
}

Output :

5
4
3
2
1
0

2. While Loop

While loop is entry controlled loop. It is Pre-Tested loop. If condition will false it will run zero times.

While-Loop controling concept

Syntax :

while(condition)
{
 //your code here
}

while:

This keyword is used to indicate the beginning of a while loop.

condition:

This is an expression that is evaluated before each iteration of the loop. If the condition evaluates to True, the loop body is executed. If it evaluates to False, the loop terminates, and program control moves to the next statement after the loop.

{}: Curly braces

These are used to enclose the block of code that will be executed repeatedly as long as the condition specified in the while statement is true. All statements within this block must be enclosed within these braces.

Check the examples below 👇

Example :

#include <stdio.h>

int main() {

    int i=0;

    while(i<5)
    {
        printf("\n%d",i);

        i++;
    }
    return 0;
}

Output : 0
1
2
3
4

3. Do-While Loop

do-while loop is exit-controlled loop. It is Post-Tested loop. If condition will false it will run ones.

Do-While-Loop controlling concept

Syntax of Do-While-Loop

do {

    // code to be executed

   }

    while (condition);

do-while-loop can be classified in three points

1. exit control loop

2. post tested

3. if condition is False , still the loop runs for at least one time

Explaination of Do-while-loop:

The code inside the loop , is executed first , then it will check the condition and if the condition id true then the loop will execute again until the condition false

Check the examples below 👇

Example :

#include <stdio.h>

int main() {

    int i=0;

    do
    {
        printf("\n%d",i);

        i++;
    }

    while(i<5);

    return 0;
}

Output :

0
1
2
3
4