for Loop

C Language Control Flow 📅 May 2026 ⏱ 1 min read 🆓 Free

for Loop in C

The for loop repeats a block of code a fixed number of times. It is the most used loop when you know in advance how many iterations are needed.

Syntax — 3 Parts

for (initialization; condition; update) {
    // body — runs while condition is true
}

Part	Runs When	Example
Initialization	Once at start	int i = 1
Condition	Before EVERY iteration	i <= 10
Body	While condition is true	printf("%d", i)
Update	After EVERY iteration	i++

Complete for Loop Examples

#include <stdio.h>

int main() {
    int i;
    
    // Count 1 to 10
    printf("Count up  : ");
    for (i = 1; i <= 10; i++)  printf("%d ", i);
    printf("\n");
    
    // Count down
    printf("Count down: ");
    for (i = 10; i >= 1; i--) printf("%d ", i);
    printf("\n");
    
    // Sum of 1 to 100
    int sum = 0;
    for (i = 1; i <= 100; i++) sum += i;
    printf("Sum 1 to 100 = %d\n", sum);
    
    // Multiplication table of 7
    printf("\nTable of 7:\n");
    for (i = 1; i <= 10; i++)
        printf("7 x %2d = %3d\n", i, 7*i);
    
    return 0;
}

▶ Output

Count up  : 1 2 3 4 5 6 7 8 9 10 
Count down: 10 9 8 7 6 5 4 3 2 1 
Sum 1 to 100 = 5050

Table of 7:
7 x  1 =   7
7 x  2 =  14
7 x  3 =  21
7 x  4 =  28
7 x  5 =  35
7 x  6 =  42
7 x  7 =  49
7 x  8 =  56
7 x  9 =  63
7 x 10 =  70

Nested for Loop — Star Triangle Pattern

for (int i = 1; i <= 5; i++) {
    for (int j = 1; j <= i; j++)
        printf("* ");
    printf("\n");
}