## Feb 1, 2020

### C program to print hollow right triangle number pattern

Ex: Write a C program to print hollow right triangle number pattern. How to write a C program to print hollow right triangle number pattern. C program to print hollow right triangle number pattern.

Input from user:
Enter the number:
5

Expected output:
1
12
1  3
1    4
12345

Step by step logic of the given program:

1. Accept input number from user declare variable say no.

2. Run outer for loop from 1 to no:
for(i=1;i<=no;i++)

3. Inside outer for loop run one inner for loop from 1 to i to print it like right triangle:
for(j=1;j<=i;j++)

4. Inside inner for loop, check if condition, to print only first and last number(To print it like hollow triangle):
if(j==1||j==i)
{
printf("%d",j);
}

5. For last row of the pattern check condition to print all number's:
else if(i==no)
{
printf("%d",j);
}

6. Otherwise print spaces:
else
{
printf(" ");
}

7. For next row print new line(\n):
printf("\n");

Program:

#include<stdio.h>
void main()
{
int i,j,no;

printf("Enter the number:\n");
scanf("%d",&no);

for(i=1;i<=no;i++)
{
for(j=1;j<=i;j++)
{
if(j==1||j==i)
{
printf("%d",j);
}
else if(i==no)
{
printf("%d",j);
}
else
{
printf(" ");
}
}
printf("\n");

}
}

Above Program's show's the following output:

Another program:

#include<stdio.h>
void main()
{
int i,j,no;

printf("Enter the number: \n");
scanf("\n%d",&no);

for(i=1;i<=no;i++)
{
for(j=1;j<=i;j++)
{
if(i<no&&j==i||i<no&&j==1)
{
printf("%d",i);
}
else if(i==no)
{
printf("%d",j);
}
else
{
printf(" ");
}
}
printf("\n");
}
}