Code:

#include <stdio.h>
#include <ctype.h>
void probability();
double power(double num, int exp);
int factoral(int n);
int nCr(int n, int r);
int again();
int main()
{
do
probability();
while(again());
return 0;
}
void probability()
{
const static char tri[5][6] =
{
{1, 1, 0, 0, 0, 0},
{1, 2, 1, 0, 0, 0},
{1, 3, 3, 1, 0, 0},
{1, 4, 6, 4, 1, 0},
{1, 5,10,10, 5, 1}
};
int n=0, i;
double p=-1, q;
printf("Enter a number of events: ");
while(n < 1 || n > 5) scanf("%i", &n);
printf("Enter the probability each events success: ");
while(p<0.0 || p>1.0) scanf("%lf", &p);
q = 1.0 - p;
double p1, q1, r;
for(i=0; i<=n; i++)
{
p1 = power(p, n-i);
q1 = power(q, i);
r = p1*q1*nCr(n-1, i); //THIS DOES NOT WORK
//r = tri[n-1][i]*p1*q1; //BUT THIS DOES
printf("%lf\t%i/%i\n", r, n-i, n);
}
}
double power(double num, int exp)
{
if(! exp) return 1.0;
int i;
double result = num;
for(i=1; i<exp; i++)
result *= num;
return result;
}
int factoral(int n)
{
int i, f=1;
for(i=2; i<=n; i++) f*=i;
return f;
}
int nCr(int n, int r)
{
// n!
// ___________
// r! (n-r)!
int a = factoral(n);
int b = factoral(r);
int c = factoral(n-r);
return a / (b * c);
}
int again()
{
char ch = '\0';
while(ch != 'y' && ch != 'n')
{
while((ch=getchar())!='\n');
printf("Run again? (Y/N)");
ch = getchar();
ch = tolower(ch);
}
return(ch == 'y')? 1: 0;
}

Can anyone tell me why it dosent work?