Pattern Programs in C (Nested Loops & Star Patterns)

Pattern programs are classic exercises for mastering nested loops, loop boundary indexing, and formatted terminal output in C.

Mastering nested for-loops is essential for multidimensional arrays and matrix manipulation.

This guide covers right-half pyramids, centered full pyramids, and Floyd's consecutive number triangle.

Interactive Runnable C Implementation

#include <stdio.h>

void print_right_pyramid(int rows) {
    printf("1. Right-Half Star Pyramid (Rows = %d):\n", rows);
    for (int i = 1; i <= rows; i++) {
        for (int j = 1; j <= i; j++) {
            printf("* ");
        }
        printf("\n");
    }
}

void print_full_pyramid(int rows) {
    printf("\n2. Full Centered Star Pyramid (Rows = %d):\n", rows);
    for (int i = 1; i <= rows; i++) {
        for (int space = 1; space <= rows - i; space++) {
            printf("  ");
        }
        for (int j = 1; j <= 2 * i - 1; j++) {
            printf("* ");
        }
        printf("\n");
    }
}

void print_floyd_triangle(int rows) {
    printf("\n3. Floyd's Number Triangle (Rows = %d):\n", rows);
    int num = 1;
    for (int i = 1; i <= rows; i++) {
        for (int j = 1; j <= i; j++) {
            printf("%-3d", num++);
        }
        printf("\n");
    }
}

int main(void) {
    int rows = 5;
    print_right_pyramid(rows);
    print_full_pyramid(rows);
    print_floyd_triangle(rows);
    return 0;
}

Open example in compiler

Expected Output

1. Right-Half Star Pyramid (Rows = 5):
* 
* * 
* * * 
* * * * 
* * * * * 

2. Full Centered Star Pyramid (Rows = 5):
        * 
      * * * 
    * * * * * 
  * * * * * * * 
* * * * * * * * * 

3. Floyd's Number Triangle (Rows = 5):
1  
2  3  
4  5  6  
7  8  9  10 
11 12 13 14 15