Write a function that outputs a right-side-up triangle of height n and width 2n-1; the output for n = 6 would be:

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

One possible solution:

void right_side_up(int n)
{
    int x,y;
    for (y= 1; y <= n; y++)
    {
        for (x= 0; x < n-y; x++)
            putchar(' ');
        for (x= (n-y); x < (n-y)+(2*y-1); x++)
            putchar('*');
        putchar('\n');
    }
}

Another solution:

#include<stdio.h>

int main(void) {
  int n;
  scanf("%d",&n);
  for(int i=0;i<n;i++) {
    for(int j=0;j<n-i-1;j++)
      putchar(32);
    for(int j=0;j<i*2+1;j++)
      putchar(42);
    putchar(10);
  }
  while((n=getchar())!=10);
  getchar();
  return 0;
}