it's already been developed by someone so why are you bothering to reinvent the wheel.
#include <stdio.h>
int main()
{
int i,j,k;
printf("Select Size \n");
scanf("%d",&k);
for(i=1; i<=k; i++)
{
for(j=1; j<=k-i; j++)
{
printf(" ");
}
for(j=1; j<=2*i-1; j++)
{
printf("*");
}...