Factorial (in C)

#include
#include
facto(double a,double b)
{
double c;
for(a=1; a<=c;a=a+1)
{
b=b*a;
}
return(b);
}
main()
{
clrscr();
double i,f=1,m;
printf("Enter a number ");
scanf("%lf",&m);
for(i=1; i<=m;i=i+1)
{
f=f*i;
}
printf("%lf", f);
getch();
}