C program to print a triangle

Algorithm

In the case of odd numbered line there is only one star and in case of even numbered line there are stars as many as the line number.

1 * Odd
2 ** Two stars
3 * Odd
4 **** Four stars
..........................

Two nested loops are involved. The outer loop tracks the line numbers while the inner loop prints the stars. The algorithm for printing this triangle for a given range is as follows where a variable 'x' is used for storing the number of star(s) to print -

START

Step 1 : Read n
Step 2 : Let i = 1
Step 3 : Repeat Step 3 to Step 10 for i <= n
Step 4 : if i % 2 == 0, x = i, Else x = 1
Step 5 : Let j = 1
Step 6 : Repeat Step 6 to Step 8 for j <= x
Step 7 : Print '*'
Step 8 : j = j + 1
Step 9 : Print '\n' (newline)
Step 10: i = i + 1

STOP

#include<stdio.h>
#include<conio.h>

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

clrscr();
printf("Range: ");
scanf("%d",&n);

for(i=1;i<=n;i++) // Outer loop starts
{
x=i%2?1:i;
for(j=1;j<=x;j++) // Inner loop starts
printf("*"); // Inner loop ends
printf("\n");
} // Outer loop ends
}

OUTPUT :

*
**
*
****
*
******
*
********
*
**********
Download source code here

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