Help w/ C

[Neal]

What is the mod function for?

Ex. (10*done + 9*dtwo + 8*dthr + 7*dfor + 6*dfiv + 5*dsix + 4*dsev + 3*deig + 2*dnin + dten)mod 11

 

[GiLtY]

mod function returns the remainder of the first number in the operation.

eg. 10 mod 3 returns 1.

--GiLtY

PS. forgot the mention, the remainder of the first number divided by the second.

 

[notfred]

var % 11

 

[Neal]

Trying to make a program which determines whether an ISBN number is valid. What is wrong with this:


#include <stdio.h>
#include <math.h>

int main()
{
int done, dtwo, dthr, dfor, dfiv, dsix, dsev, deig, dnin, dten, mod;

printf("Please enter a 10 digit ISBN number: \n ");
scanf("%ld%ld%ld%ld%ld%ld%ld%ld%ld%ld",&done, &dtwo, &dthr, &dfor, &dfiv, &dsix, &dsev, &deig, &dnin, &dten);

mod = (10*done + 9*dtwo + 8*dthr + 7*dfor + 6*dfiv + 5*dsix + 4*dsev + 3*deig + 2*dnin + dten)var % 11;

if (mod == 0)
printf("Valid ISBN number\n");
else
printf("Invalid ISBN number\n");

return 0;
}


Thanks

 

[notfred]

I mean "var" as some variable. like:

int var = 50;
mod = var % 11;