C program to print hollow rectangle star pattern

Here, we will print hollow rectangle star(*) pattern by using for loop in C programming language.

Consider an example given below −

Input

Enter number of rows: 5

Output

The output is as follows −

*****
*    *
*    *
*    *
*****

Algorithm

An algorithm is given below to explain how to print hollow rectangle star(*) pattern by using for loop.

Step 1 − Input number of rows to print at runtime.

Step 2 − Use outer for loop for rows from 1 to N.

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

Step 3 − Run an inner loop from 1 to N for columns.

for(j=1; j<=N; j++).

Step 4 − Inside inner loop print star for first and last row or for first and last column.

        Otherwise, print space.

Step 5 − After printing all columns of a row, move to next line.

Program

Following is the C program to print hollow rectangle star(*) pattern by using for loop −

#include <stdio.h>
int main(){
   int i, j, N;
   printf("Enter number of rows: ");
   scanf("%d", &N);
   for(i=1; i<=N; i++) {
      for(j=1; j<=N; j++){
         if(i==1 || i==N || j==1 || j==N){
            printf("*");
         }
         else{
            printf(" ");
         }
      }
      printf("
");
   }
   return 0;
}

Output

When the above program is executed, it produces the following result −

Enter number of rows: 6
******
*    *
*    *
*    *
*    *
******