C program to print diamond star pattern 
    *
   ***
  *****
 *******
*********
 *******
  *****
   ***
    *

C Programming Language Loop control in C Language (Article) Loop control in C Language (Program)

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Program:

/**
 * C program to print diamond star pattern 
 */

#include <stdio.h>

int main()
{
    int i, j, rows;
    int stars, spaces;
   
    printf("Enter rows to print : ");
    scanf("%d", &rows);
    
    
    stars = 1;
    spaces = rows - 1;
    
    /* Iterate through rows */
    for(i=1; i<rows*2; i++)
    {
        /* Print spaces */
        for(j=1; j<=spaces; j++)
            printf(" ");
        
        /* Print stars */
        for(j=1; j<stars*2; j++)
            printf("*");
        
        /* Move to next line */
        printf("\n");
        
        if(i<rows)
        {
            spaces--;
            stars++;
        }
        else
        {
            spaces++;
            stars--;
        }
    }
    
    return 0;
}

Output:

Enter N: 5
    *
   ***
  *****
 *******
*********
 *******
  *****
   ***
    *

Explanation:

Required knowledge

Basic C programming, If else, For loop, Nested loop

Logic to print diamond star pattern

 

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    *

 

The given pattern is a combination of simple pyramid star pattern and inverted pyramid star pattern. It consist of N*2-1 rows (for this case N=5). Each row contain spaces and stars in printed in increasing and decreasing order.

Stars are printed in increasing order till Nth row. After Nth row stars are printed in decreasing order.

Spaces are printed in decreasing order till Nth row. After Nth row spaces are printed in increasing order. Point your mouse cursor over the pattern to count total spaces.

Step by step descriptive logic to print diamond star pattern.

  1. Input number of rows to print from user (in real number of rows/2). Store it in a variable say rows.
  2. Declare two variables to keep track of total columns to print each row, say stars=1 and spaces=N-1.
  3. To iterate through rows, run an outer loop from 1 to rows*2-1. The loop structure should look like for(i=1; i<rows*2; i++).
  4. To print spaces, run an inner loop from 1 to spaces. The loop structure should look like for(j=1; j<=spaces; j++). Inside this loop print single space.
  5. To print stars, run another inner loop from 1 to stars*2-1. The loop structure should look like for(j=1; j<=stars; j++). Inside this loop print star.
  6. After printing all colu

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