C Nested Loop

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Nested loops in C involve placing one loop inside another loop. Each type of loop (for, while, or do-while) can be nested inside any other type. Nesting loops are useful for problems involving multi-dimensional data structures or complex iteration patterns.

1. Nested for Loops

A nested for loop means placing one for loop inside another for loop. Here's an example that prints a multiplication table up to a specified number of rows and columns:

#include <stdio.h>

int main() {
    int rows, columns;

    printf("Enter the number of rows: ");
    scanf("%d", &rows);

    printf("Enter the number of columns: ");
    scanf("%d", &columns);

    // Nested for loop to generate a multiplication table
    for (int i = 1; i <= rows; i++) {
        for (int j = 1; j <= columns; j++) {
            printf("%d\\t", i * j); // Print product of i and j
        }
        printf("\\n"); // New line after each row
    }

    return 0;
}

Output:

Enter the number of rows: 3
Enter the number of columns: 3
1 2 3
2 4 6
3 6 9

2. Nested while Loops

A nested while loop means placing one while loop inside another while loop. Here's an example that prints a pattern of numbers:

#include <stdio.h>

int main() {
    int rows, columns;
    int number = 1;

    printf("Enter the number of rows: ");
    scanf("%d", &rows);

    printf("Enter the number of columns: ");
    scanf("%d", &columns);

    // Nested while loop to print a pattern of numbers
    int i = 1;
    while (i <= rows) {
        int j = 1;
        while (j <= columns) {
            printf("%d\\t", number);
            number++;
            j++;
        }
        printf("\\n"); // New line after each row
        i++;
    }

    return 0;
}

output:

Enter the number of rows: 3
Enter the number of columns: 5
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15

3. Nested do-while Loops

A nested do-while loop means placing one do-while loop inside another do-while loop. Here's an example that prints a pattern of asterisks (*):

#include <stdio.h>

int main() {
    int i, j;

    // Outer loop for rows
    do {
        // Inner loop for columns
        j = 1; // Initialize inner loop variable
        do {
            printf("%d\\t", j); // Print the number
            j++; // Increment inner loop variable
        } while (j <= 10); // Condition for inner loop

        printf("\\n"); // Move to the next line after inner loop finishes

        i++; // Increment outer loop variable
    } while (i <= 10); // Condition for outer loop

    return 0;
    }

Output:

1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10

Key Points:

• Complexity: The complexity increases with nested loops. Be mindful of performance and ensure that the loop conditions are set correctly to avoid infinite loops.

• Initialization: Properly initialize loop variables and ensure they are updated within the loop to avoid unexpected behavior.

• Output: Carefully consider the output format and spacing, especially when dealing with nested loops.

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