Nested loops and complex control flow

Here’s an example of nested loops and complex control flow in C. This code generates a multiplication table for numbers from 1 to 5 and includes an example of using break and continue to manage control flow.

#include <stdio.h>

int main() {
    int i, j;

    printf("Multiplication Table (1 to 5):\n");

    // Outer loop to iterate through rows (multipliers)
    for (i = 1; i <= 5; i++) {
        // Inner loop to iterate through columns (multiplicands)
        for (j = 1; j <= 5; j++) {
            // Example of control flow using "continue" and "break"
            if (j == 3) {
                continue;  // Skip when j is 3, so 3 times any number isn't shown
            }
            if (i == 4) {
                break;  // Exit inner loop if i is 4, so row 4 is incomplete
            }
            printf("%d x %d = %2d\t", i, j, i * j);
        }
        printf("\n");
    }

    return 0;
}

Explanation of Nested Loops and Complex Control Flow

1. Nested Loops

• Outer Loop (for loop with variable i): Controls the rows in the table. It iterates from 1 to 5, representing the multiplier.
• Inner Loop (for loop with variable j): Controls the columns in each row. It iterates from 1 to 5, representing the multiplicand for each multiplier in the outer loop.
• Output: The combination of the two loops generates pairs (i, j) to compute the product i * j, and the results are displayed in a tabular format.

2. Control Flow Statements

• continue: The continue statement in the inner loop skips the current iteration when j == 3. This prevents printing any products where j = 3 (i.e., i * 3 values). Effect: The program skips calculations for 3 in each row, leaving the output without columns for 3.

• break: The break statement in the inner loop stops the inner loop immediately when i == 4. Effect: The row corresponding to i = 4 will not have any printf statements, will print empty spaces.

Output of the Program

The output will look something like this, illustrating the skipped and broken values:

Multiplication Table (1 to 5):
1 x 1 =  1    1 x 2 =  2    1 x 4 =  4    1 x 5 =  5    
2 x 1 =  2    2 x 2 =  4    2 x 4 =  8    2 x 5 = 10    
3 x 1 =  3    3 x 2 =  6    3 x 4 = 12    3 x 5 = 15    
   
5 x 1 =  5    5 x 2 = 10    5 x 4 = 20    5 x 5 = 25

Summary of Nested Loops and Complex Control Flow

• Nested Loops: Used here to create a multiplication table by combining i and j.
• continue Statement: Skips an iteration within a loop, selectively omitting results when certain conditions are met.
• break Statement: Exits the loop when a condition is met, as seen with i == 4 to terminate the row early.

This example demonstrates how nested loops and control flow statements like break and continue can create complex behavior in structured, repeatable operations.