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C program to print hollow pyramid (Equilateral triangle) star pattern 
    *
   * *
  *   *
 *     *
*********

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Write a C program to print hollow pyramid or hollow equilateral triangle star pattern series using for loop. How to print hollow pyramid star pattern series in C program. Logic to print hollow pyramid star pattern series in C programming.

Program Code

/**
 * C program to print hollow pyramid triangle star pattern
* atnyla.com
 */

#include <stdio.h>

int main()
{
    int i, j, rows;

    /* Input rows to print from user */
    printf("Enter number of rows : ");
    scanf("%d", &rows);

    for(i=1; i<=rows; i++)
    {
        /* Print trailing spaces */
        for(j=i; j<rows; j++)
        {
            printf(" ");
        }

        /* Print hollow pyramid */
        for(j=1; j<=(2*i-1); j++)
        {
            /*
             * Print star for last row (i==rows),
             * first column(j==1) and for
             * last column (j==(2*i-1)).
             */ 
            if(i==rows || j==1 || j==(2*i-1))
            {
                printf("*");
            }
            else
            {
                printf(" ");
            }
        }

        /* Move to next line */
        printf("\n");
    }

    return 0;
}

Output

Enter number of rows: 5
    *
   * *
  *   *
 *     *
*********

Explanation

Required knowledge

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

Logic to print hollow pyramid star pattern

 

    *
   * *
  *   *
 *     *
*********

 

The above pattern is similar to pyramid star pattern except of center spaces.

Step by step descriptive logic to print hollow pyramid star pattern.

  1. Input number of rows to print from user. Store it in a variable say rows.
  2. To iterate through rows run an outer loop from 1 to rows. The loop structure should look like for(i=1; i<=rows; i++).
  3. To print spaces, run an inner loop from i to rows - 1. The loop structure should look like for(j=i; j. Inside this loop print single space.
  4. To print star, run another inner loop from 1 to i * 2 - 1. The loop structure should look like for(j=1; j<=(i*2-1); j++). Inside this loop print star for ith or last column or for last row.
  5. After printing all columns of a row, move to next line i.e. print new line.

How to learn from this program

First read the algorithm, then study the program code line by line. After that, compare the code with the output and finally go through the explanation. This approach helps learners understand both the logic and the implementation properly.

Quick Practice Flow

Use this small plan to get the best result from the program example.

  • Read the title and topic first
  • Understand the algorithm carefully
  • Study the code line by line
  • Check the output and compare the logic

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