C program to print hollow inverted pyramid star pattern

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

Input rows: 5

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

Required knowledge

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

Must know – Program to print hollow pyramid pattern.

Logic to print hollow inverted pyramid star pattern

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

The above pattern is similar to inverted pyramid star pattern except spaces are printed in center of the pyramid.

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 leading spaces, run an inner loop from 1 to i - 1. The loop structure should look like for(j=1; j<i; j++). Inside this loop print single space.
4. To print stars, run another inner loop from 1 to rows * 2 - (i * 2 - 1). The loop structure should look like for(j=1; j<=(rows*2-(i*2-1)); j++).

   Inside this loop print star for i^th and last column and for first row otherwise print space.

5. After printing all columns of a row, move to next line i.e. print new line.

Program to print hollow inverted pyramid star pattern

/**
 * C program to print hollow inverted pyramid star pattern
 */

#include <stdio.h>

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

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

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

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

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

    return 0;
}

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

Happy coding 😉