m阶乘除以n的阶乘与m-n的阶乘的乘积

#include
#include
float fun( int m, int n)
{ float p,t=1.0;
int i;
for(i=1;i<=m;i++)
t=t*i;
p=t;
for(t=1.0,i=1;i<=n;i++)
t=t*i;
p=p/t;
for(t=1.0,i=1;i<=m-n;i++)
t=t*i;
p=p/t;
return p;
}
main()
{
FILE *out;
printf("P=%f\n", fun(12,8));
out = fopen("out.dat", "w");
fprintf(out, "%f", fun(12,8));
fclose(out);
}