13.Hollow Triangle

 

Steps

• Let's count the number of lines i.e 9 so we take it as n
• So i will iterate from 1 to n
• The pattern printed never exceeds i
• For i=1 it is 1, i=9 pattern is there till 9
• So j loop will iterate from 1 to i
• Now coming to the pattern
• We will see where stars are being printed 
• First vertical line i.e for j=1 each time
• Next horizontal line i.e i=n (i=9 in our example)
• Finally there is a diagonal values 1==1,2==2 so it is i=j
• We will use these conditions in a if condition using logical or
• True part will print *
• False part will print space

Code

#include<stdio.h>

#include<conio.h>

void main(){

int i,j,n;

clrscr();

printf("Enter number of lines ");

scanf("%d",&n);

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

    {

          for(j=1;j<=i;j++)

               {

                              if(i==n || j==1 || i==j)

                                     {

                                       printf("*");

                                       }

                                else

                                       {

                                         printf(" ");

                                         }   

                   }

           printf("\n");

     }

getch();

}

Note: scanf is used for taking user input