How to write “nested loop” in C programming language?

Nested Loop

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Nested For Loop

#include <stdio.h>
    int main() {
        int i, j;
        for (i = 1; i <= 3; i++) {                  // Outer loop
            printf("Outer loop: %d\n", i);
            for (j = 1; j <= 3; j++) {              // Inner loop
                printf("Inner loop: %d\n", j);
            }
            printf("\n");
        }
        return 0;
    }

Output

Outer loop: 1
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3
    
    Outer loop: 2
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3
    
    Outer loop: 3
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3

Nested While Loop

#include <stdio.h>
    int main() {
        int i = 1, j;
        while (i <= 3) {                            // Outer loop
            printf("Outer loop: %d\n", i);
            j = 1;
            while (j <= 3) {                        // Inner loop
                printf("Inner loop: %d\n", j);
                j++;
            }
            i++;
            printf("\n");
        }
        return 0;
    }

Output

Outer loop: 1
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3
    
    Outer loop: 2
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3
    
    Outer loop: 3
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3

Nested do-while Loop

#include <stdio.h>
    int main() {
        int i = 1, j;
        do {                                    // Outer loop
            printf("Outer loop: %d\n", i);
            j = 1;
            do {                                // Inner loop
                printf("Inner loop: %d\n", j);
                j++;
            } while (j <= 3);
            i++;
              printf("\n");
        } while (i <= 3);
      
        return 0;
    }

Output

Outer loop: 1
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3
    
    Outer loop: 2
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3
    
    Outer loop: 3
    Inner loop: 1
    Inner loop: 2
    Inner loop: 3