[c-prog] Re: an example about factorial numbers

[ruhatadiyaman]

thanks for all replies. i tried them but still the problem is continuing. this 
is my code with 'unsigned long int';
/*factorial*/
#include<stdio.h>
int main()
{
     int x, y;
    unsigned long int fak;
    
    for(x=1;x<=20;x++){
                      printf("%d!\t", x);
                      fak=x;
                      if(x>=2){
                      for(y=x;y>=2;y--){
                                        fak=fak*(y-1);
                                        }
                                        }
                      printf("%lu\n", fak);
                      }
    getch();
    return 0;
}

so after 13 the results are wrong :(
otherwise i confused with usage of long double. i wrote this simple code which 
is below;
#include<stdio.h>
int main()
{
    
long double x, y;
scanf("%Lf", &x);
scanf("%Lf", &y);
printf("x=%Lf y=%Lf\n", x, y);
printf("result=%Lf", x*y);
getch();
}

when i run it,for example, i give 2 for x and 4 for y,the program gives this;
x=2.000000  y=0.000000
result=-2.000000

what's this?

best regards