Program to print solid and hollow rhombus patterns in C

A rhombus pattern in C is a diamond-like shape created using stars (*). There are two types: solid rhombus (completely filled with stars) and hollow rhombus (only the border is filled with stars).

Syntax

// Nested loops to create rhombus pattern
for(row = 1; row <= n; row++) {
    // Print leading spaces
    for(space = 1; space <= n - row; space++) {
        printf(" ");
    }
    // Print stars or spaces based on pattern type
    for(col = 1; col <= n; col++) {
        // Logic for solid or hollow pattern
    }
    printf("<br>");
}

Example 1: Hollow Rhombus Pattern

In a hollow rhombus, only the first row, last row, first column, and last column contain stars −

#include <stdio.h>

int main() {
    int rows = 5;
    int r, c;
    
    printf("Hollow Rhombus Pattern:<br>");
    
    for(r = 1; r <= rows; r++) {
        /* Print leading spaces */
        for(c = 1; c <= rows - r; c++) {
            printf(" ");
        }
        
        /* Print stars and spaces */
        for(c = 1; c <= rows; c++) {
            if(r == 1 || r == rows || c == 1 || c == rows) {
                printf("*");
            } else {
                printf(" ");
            }
        }
        printf("<br>");
    }
    
    return 0;
}

Hollow Rhombus Pattern:
    *****
   *   *
  *   *
 *   *
*****

Example 2: Solid Rhombus Pattern

In a solid rhombus, all positions are filled with stars −

#include <stdio.h>

int main() {
    int rows = 5;
    int r, c;
    
    printf("Solid Rhombus Pattern:<br>");
    
    for(r = 1; r <= rows; r++) {
        /* Print leading spaces */
        for(c = 1; c <= rows - r; c++) {
            printf(" ");
        }
        
        /* Print stars */
        for(c = 1; c <= rows; c++) {
            printf("*");
        }
        printf("<br>");
    }
    
    return 0;
}

Solid Rhombus Pattern:
    *****
   *****
  *****
 *****
*****

Example 3: Combined Program with User Input

This program demonstrates both patterns with user-specified dimensions −

#include <stdio.h>

int main() {
    int rows = 4;
    int r, c;
    
    printf("Number of rows: %d<br><br>", rows);
    
    /* Hollow Rhombus */
    printf("Hollow Rhombus Pattern:<br>");
    for(r = 1; r <= rows; r++) {
        for(c = 1; c <= rows - r; c++) {
            printf(" ");
        }
        for(c = 1; c <= rows; c++) {
            if(r == 1 || r == rows || c == 1 || c == rows) {
                printf("*");
            } else {
                printf(" ");
            }
        }
        printf("<br>");
    }
    
    printf("<br>");
    
    /* Solid Rhombus */
    printf("Solid Rhombus Pattern:<br>");
    for(r = 1; r <= rows; r++) {
        for(c = 1; c <= rows - r; c++) {
            printf(" ");
        }
        for(c = 1; c <= rows; c++) {
            printf("*");
        }
        printf("<br>");
    }
    
    return 0;
}

Number of rows: 4

Hollow Rhombus Pattern:
   ****
  *  *
 *  *
****

Solid Rhombus Pattern:
   ****
  ****
 ****
****

How It Works

• Outer loop: Controls the number of rows
• First inner loop: Prints leading spaces to create the slanted effect
• Second inner loop: Prints stars (*) or spaces based on pattern type
• Hollow condition: Stars only on borders (first/last row/column)
• Solid condition: Stars in all positions

Conclusion

Rhombus patterns in C use nested loops to create geometric shapes. The key is controlling spaces for alignment and applying conditions for hollow versus solid patterns.