C Program to print Hollow Hourglass pattern

   C  Program Hollow Hourglass pattern  

C Program to print Hollow Hourglass pattern 
Example :-

#include <stdio.h>

 

int main()

{

  int i, j, k, rows;

 

  printf("Enter the no. of rows: ");

  scanf("%d", &rows);

 

  printf("Output: \n\n");

 

  for (i = 1; i <= rows; i++)

  {

    for (k = 1; k < i; k++)

      printf(" ");

 

    for (j = i; j <= rows; j++)

      printf("* ");

 

    printf("\n");

  }

 

  for (i = rows - 1; i >= 1; i--)

  {

    for (k = 1; k < i; k++)

      printf(" ");

 

    for (j = i; j <= rows; j++)

      printf("* ");

 

    printf("\n");

  }

 

  return 0;

}

C Code for Printing a Hollow Hourglass Shape

Explain Program

Step :1

Variable Declarations:

int i, j, k, rows;

• i, j, k: Loop control variables

• rows: Number of rows (input from the user)

Step :2

 Input from the user:

printf("Enter the no. of rows: ");

scanf("%d", &rows);

• The user is ask to input the total number of row.

• 
  
• example, if rows = 4, the pattern 

• 4 rows in the upper part

• 3 rows in the lower part

Step :3

heading:

printf("Output: \n\n");

 heading for clarity.

Step :4

 Upper Part of the Pattern:

for (i = 1; i <= rows; i++)

{

    for (k = 1; k < i; k++)

        printf(" ");

     for (j = i; j <= rows; j++)

        printf("* ");

    printf("\n");

}

loop prints an inverted right-aligned triangle of stars.

• i goes from 1 to rows — each iteration is a new row.

• k prints spaces before the stars. The number of spaces increases each row to push the stars to the right.

        j prints * from the current row number to rows. So, stars decrease in each row

Step :5

Lower Part of the Pattern:

for (i = rows - 1; i >= 1; i--)

{    for (k = 1; k < i; k++)

        printf(" ");

     for (j = i; j <= rows; j++)

        printf("* ");

     printf("\n");

}

 loop prints a right-aligned triangle of stars

This loop prints a right-aligned triangle of stars (opposite of the first).

• Starts from rows - 1 and goes down to 1.

• In each row:

• Prints spaces first (decreasing).

• Then prints stars (increasing count).

C Program to print Hollow Hourglass pattern 
Output :-

C Program to print Hollow Hourglass pattern 
Summary 

• The upper triangle shrinks (top-down).

• The lower triangle grows (bottom-up).

• Both are right-aligned because of the space handling (printf(" ")).

• Nested loops (loop inside loop)

• Controlling spaces and stars to format patterns

• Symmetry in output (first half decreasing, second half increasing)

• User input and loops for dynamic patterns

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