Triangle Printing In C

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This section will deal to enhance understanding of loops and nested loops. We shall print various pattern to learn how loops in C works.

Equilateral Triangle

#include <stdio.h>

int main()
{
	int n,i,j;
	printf("Enter number of rows: ");
	scanf("%d",&n);
	
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=n-i;j++)
			printf(" ");
			
		for(j=1;j<=i;j++)
			printf("* ");
			
		printf("\n");
	}
return 1;
}

The output should look like this −

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

Upside Down Triangle

This program will print a triangle in upside down

#include <stdio.h>

int main()
{
	int n,i,j;
  
  n = 5;
	
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=n-i;j++)
			printf(" ");
			
		for(j=1;j<=i;j++)
			printf("* ");
			
		printf("\n");
	}
return 1;
}

The output should look like this −

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

Right Triangle

#include <stdio.h>
int main()
{
	int n,i,j;
  
  n = 5;

	for(i=1;i<=n;i++)
	{
		for(j=1;j<=i;j++)
			printf("*");
			
		printf("\n");
	}
return 0;
}

The output should look like this −

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

Top-Down Right Triangle

#include <stdio.h>
int main()
{
	int n,i,j;

   n = 5;
	
	for(i=n;i>=1;i--)
	{
		for(j=1;j<=i;j++)
			printf("*");
			
		printf("\n");
	}
return 0;
}

The output should look like this −

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

Top-Down Right Triangle - 2

#include <stdio.h>

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

   n = 5;
	
   for(i = 0; i < n; i++)
   {
      for(j=0; j<i; j++)
      {
         printf("  "); 
      }

      for(j=i; j < n; j++)
      {
         printf(" *");
      }

      printf("\n");
   }
return 0;
}

The output should look like this −

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

Floyd's Triangle

#include <stdio.h>

int main()
{
	int n,i,j,k=1;

   n = 5;

	for(i = 1; i<=n;i++)
	{
		for(j=1;j< =i;j++)
			printf("%3d",k++);
			
		printf("\n");
	}
return 0;
}

The output should look like this −

  1
  2  3
  4  5  6
  7  8  9 10
 11 12 13 14 15

Pascal's Triangle

#include <stdio.h>

int factorial(int n)
{
	int f;
	for(f=1;n>1;n--)
		f*=n;
return f;
}

int ncr(int n,int r)
{
	return factorial(n)/(factorial(n-r)*factorial(r));
}

int main()
{
	int n,i,j;
	
  n = 5;
	
	for(i=0;i<=n;i++)
	{
		for(j=0;j<=n-i;j++)
			printf("  ");
		for(j=0;j<=i;j++)
			printf("%4d",ncr(i,j));
	
	 printf("\n");
	}
return 0;
}

The output should look like this −

               1
             1   1
           1   2   1
         1   3   3   1
       1   4   6   4   1
     1   5  10  10   5   1