Looping in C Programming

Looping in C allows a set of instructions to be executed repeatedly based on a condition. This is useful for tasks that require repetitive execution, such as iterating over an array or performing calculations multiple times.

---

Types of Loops in C

C provides three types of loops:

1. for Loop
2. while Loop
3. do-while Loop

---

1. for Loop

The for loop is used when the number of iterations is known beforehand.

Syntax:

• Initialization: Sets the starting point of the loop.
• Condition: Determines whether the loop should continue.
• Increment/Decrement: Updates the loop control variable.

Example: Printing Numbers 1 to 5

#include <stdio.h>

int main() {
for (int i = 1; i <= 5; i++) {
printf(“%d\n”, i);
}
return 0;
}

Output:

1
2
3
4
5

---

2. while Loop

The while loop is used when the number of iterations is not known beforehand, and it continues until the condition becomes false.

Syntax:

Example: Printing Numbers 1 to 5

#include <stdio.h>

int main() {
int i = 1;
while (i <= 5) {
printf(“%d\n”, i);
i++; // Increment the counter
}
return 0;
}

Output:

1
2
3
4
5

---

3. do-while Loop

The do-while loop is similar to the while loop but guarantees that the code inside the loop is executed at least once, regardless of the condition.

Syntax:

Example: Printing Numbers 1 to 5

#include <stdio.h>

int main() {
int i = 1;
do {
printf(“%d\n”, i);
i++; // Increment the counter
} while (i <= 5);
return 0;
}

Output:

1
2
3
4
5

---

Comparison of Loops

Type of Loop	When to Use	Condition Check
for Loop	When the number of iterations is known beforehand.	Before each iteration.
while Loop	When the number of iterations is not fixed and depends on a condition.	Before each iteration.
do-while Loop	When the loop must execute at least once, regardless of the condition.	After each iteration.

---

Special Statements in Loops:

1. break:
   • Exits the loop immediately.
   • Example:
     for (int i = 1; i <= 5; i++)

     {


     if (i == 3)

     break; // Exit loop when i equals 3


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


     }


     Output:

     1


     2
2. continue:
   • Skips the rest of the code in the current iteration and moves to the next iteration.
   • Example:
     for (int i = 1; i <= 5; i++)

     {


     if (i == 3)

     continue;

     // Skip iteration when i equals 3


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


     }


     Output:

     1


     2


     4


     5

     ---

     Summary

     • for Loop: Best for fixed iterations.
     • while Loop: Best for conditions with unknown iterations.
     • do-while Loop: Ensures at least one execution before checking the condition.
     • Control Statements: break and continue modify the flow of loops