C For Loop

Prev Next

The for loop in C is a control flow statement that allows you to execute a block of code repeatedly for a fixed number of times or based on a condition. It is particularly useful for iterating over arrays, lists, and performing repetitive tasks.

Syntax:

for (initialization; condition; increment/decrement) {
// Code to be executed
}

• Initialization: Sets up the loop control variable.

• Condition: Evaluated before each iteration; if true, the loop continues; if false, the loop ends.

• Increment/Decrement: Updates the loop control variable after each iteration.

Flowchart of the for Loop

he flowchart for a for loop in C illustrates the process:

1. Initialization: Set up the loop control variable.

2. Condition Check: Evaluate the loop condition.

     • If true, proceed to execute the loop body.

     • If false, exit the loop.

3. Execution: Execute the loop body.

4. Update: Modify the loop control variable.

5. Repeat: Go back to the condition check.

Examples of for Loop

Example 1: Print Numbers 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

Example 2: Print Multiplication Table

#include <stdio.h>

int main() {
    int i, number;

    // Prompt user for input
    printf("Enter a number: ");

    // Check if input is successfully read
    if (scanf("%d", &number) != 1) {
        printf("Invalid input. Please enter an integer.\\n");
        return 1; // Return error code
    }

    // Print multiplication table
    for (i = 1; i <= 10; i++) {
        printf("%d x %d = %d\\n", number, i, number * i);
    }

    return 0;
}

Output:

Enter a number: 3
3 x 1 = 3
3 x 2 = 6
3 x 3 = 9
3 x 4 = 12
3 x 5 = 15
3 x 6 = 18
3 x 7 = 21
3 x 8 = 24
3 x 9 = 27
3 x 10 = 30

Example 3: Print a Pattern

#include <stdio.h>

int main() {
    int i, j;

    for (i = 1; i <= 5; i++) { // Number of rows
        for (j = 1; j <= i; j++) { // Print stars in each row
            printf("*");
        }
        printf("\\n"); // Move to the next line
    }

    return 0;
}

Output:

*
**
***
****
*****

Key Points to Remember

• Initialization: Typically used to set a loop control variable.

• Condition: Evaluated before each iteration; if false, the loop terminates.

• Increment/Decrement: Used to update the loop control variable each iteration.

• Scope of Variables: The loop control variable is local to the for loop block unless defined outside.

Prev Next