Floyd’s Triangle in C

Program to display Floyd’s triangle pattern in C language. There are many programming exercises in the C programming language which involve printing a particular pattern in the console. Floyd’s triangle is one of them. It is based on displaying a pattern of half a pyramid of numbers.

Floyd’s triangle is a right angle triangle of an array of natural numbers. In Floyd’s triangle nth row contents n elements.

C Program For Floyd’s Triangle

#include<stdio.h>
int main()
{
   int n, i, j, a=1;
   printf("Enter the number of rows: ");
   scanf("%d",&n);
   for(i=1; i<=n; i++)
   {
     for(j=1; j<=i; j++)
     printf("%-5d",a++);
     printf("\n");
   }
   return 0;
}

Output for different test-cases:-

Enter the number of rows: 5
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15

Enter the number of rows: 7
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15
16 17 18 19 20 21
22 23 24 25 26 27 28

Floyd Triangle in C Explanation

To print Floyd’s triangle in C, the nested loop is required. The outer loop represents the row and the inner loop represents the column. The Floyd’s triangle starts with 1 and every nth row contains n elements. So, the outer loop starts with i=1 and iterate n times. The inner loop starts with j=1 and iterates i times.

In this program, the width modifier is used with printf function, and the display is left-justified to the console. Read More:- Output formatting using printf function in C

Floyd’s triangle in C using recursion

Using recursion we can display Floyd’s triangle. Read more:- Recursion in C

#include<stdio.h>
int row=1;
int a = 1;
void printFloyd(int n)
{
  if(n<=0) return;

  for(int i=1; i<=row; i++)
  printf("%-5d",a++);

  printf("\n");
  row++;
  printFloyd(n-1);
}

int main()
{
  int n;
  printf("Enter number of rows: ");
  scanf("%d",&n);
  printFloyd(n);
  return 0;
}

Reverse Floyd’s triangle in C

Sample of Input/Output:-

Enter number of rows: 5
15 14 13 12 11
10 9 8 7
6 5 4
3 2
1

Enter number of rows: 7
28 27 26 25 24 23 22
21 20 19 18 17 16
15 14 13 12 11
10 9 8 7
6 5 4
3 2
1

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

   printf("Enter number of rows: ");
   scanf("%d",&n);

   int k = n*(n+1)/2;
   for(i=n; i>=0; i--)
   {
     for(j=1; j<=i; j++)
     printf("%-5d",k--);
     printf("\n");
   }

   return 0;
}

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