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(Part 4 of this series of Q-A is here: 16 marks, Q-A, structures in C, Unit 4. )
16 marks Q-A on loops (Unit 1), Nov/Dec 2022, Anna Univ, CS 3251 (Programming in C)
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Anna University Past Years Exam Q & A

CS3251 : Programming in C

Nov / Dec 2022, 16 Marks, Unit 1

Question

Explain the looping statement in C with suitable examples.

Answer

• Loops help us to easily execute a block of code repeatedly.
• The code is repeatedly executed as long as the loop condition is true.
• Loops help to make the program shorter, easier to read, and easier to maintain.

There are 3 loops in C:

• for
• while
• do-while

for loop:

• Initialization, checking of condition, and updation is written compactly in a single line.

// Prints numbers from 1 to 5.
#include <stdio.h>
int main()
{
    int i;
    for (i = 1; i <= 5; i++)
    {
        printf("%d\n", i);
    }
    return 0;
}

output: 
1
2
3
4
5

while loop

• Condition is checked before executing the statements within the loop body.

// Prints numbers from 1 to 5.
#include <stdio.h>
int main()
{
    int i = 1;
    while (i <= 5)
    {
        printf("%d\n", i);
        i++;
    }
    return 0;
}

output:
1
2
3
4
5

do-while loop

• condition is checked after executing the statements within the loop body.
• The loop body necessarily gets executed at least once.

// Prints numbers from 1 to 5.
#include <stdio.h>
int main()
{
    int i = 1;
    do
    {
        printf("%d\n", i);
        i++;
    } while (i <= 5);
    return 0;
}

output: 
1
2
3
4
5

(Next part of this series is here: Part 6, Functions (Unit 3), 16 marks Q&A)