Thread: Assigning values to functions (Newbie)

I have just started learning C and I already have some issues.

Code:

#include <stdio.h>

int binom(int n, int k)
{
int result=1;
int i;
if(n == k) return 1;
if(k == 0) return 1;
for(i=n;i>n-k;i--)
result=result*i;
for(i=1;i<=k;++i)
result=result/i;
return result;
}


int main(void)
{
int bnm;
int n, k;
for(n=0;n<10;n++){
for(k=0;k<=n;k++){
bnm=binom(n,k);
printf("%ld ",bnm);
}
printf("\n");
}
return 0;
}

I understand that variables "n" and "k" from "main" and "binom" function are different but does the line:

Code:

bnm=binom(n,k);

mean it will assign "n" value from "main" function to "binom" function? (Same applies to "k")
I know this is stupid question, and yes I googled it but I havent found a decent answer. Thanks.

Thanks!
One more question. I don't understand the logic behind this... In the "main" function we keep incrementing n and k at the same rate until n=9.
Shouldn't that keep the ratio of n and k equal (n==k) and therefore always return 1?
I know I got something wrong but I'm not sure what...

Originally Posted by turke92

Thanks!
One more question. I don't understand the logic behind this... In the "main" function we keep incrementing n and k at the same rate until n=9.
Shouldn't that keep the ratio of n and k equal (n==k) and therefore always return 1?
I know I got something wrong but I'm not sure what...

If you would learn to indent your code properly you would actually be able to see what is happening...

Code:

#include <stdio.h>

int binom(int n, int k)
{
   int result=1;
   int i;

   if(n == k) 
     return 1;

   if(k == 0) 
     return 1;

   for(i=n;i>n-k;i--)
     result=result*i;
   for(i=1;i<=k;++i)
     result=result/i;
   return result;
}


int main(void)
{
   int bnm;
   int n, k;

   for(n=0;n<10;n++) 
     {
       for(k=0;k<=n;k++)
         {
           bnm=binom(n,k);
           printf("%ld ",bnm);
         }
       printf("\n");
    }
   return 0;
}

See it now? the k loop is inside the n loop... for each value of n you call binom with every value of k.

So that means that after testing if n<10 is true the program solves the "binom" function and prints it, increments n, goes into a new line, and after all that it looks if k<=n and does the orders in its brackets? I'm sorry if you find it difficult to understand my stupid question regarding this simple issue.

EDIT: "See it now? the k loop is inside the n loop... for each value of n you call binom with every value of k." I think I speak english well but this statement confused me and hence my even more confusing question.

Here try this little code snippet...

Code:

#include <stdio.h>

int main (void)
  { int i, j;

    for (i = 0; i < 5; i++)
       for (j = 0; j< i; j++)
          printf( " i = %d, j = %d \t",i,j);

   getchar();
   return 0;
}

Get it now?

So initialization of "j" (j = 0) is made every time if the statement "j < i" is false and initialization of "i" is done only once?

Originally Posted by turke92

So initialization of "j" (j = 0) is made every time if the statement "j < i" is false and initialization of "i" is done only once?

Initialization is done only at the beginning of a for() loop... any for() loop, every for() loop...

You have two loops, one running inside the other...
Look at the way the numbers count up...

Now apply that to your original code...

I got it but I haven't said what I meant right.
I thought that the value of j stays saved if we get back to the first loop, I didn't know that after we get back to the second loop initialization is made again.

Thanks for helping!

No j is not saved because you don't go back to the outer loop until the inner one is finished and each time you re-enter the inner loop it's starting over... the numerical printout from my example should have demonstrated that very clearly.

Like I said, I got it now, but didn't know this when I encountered the code on the 1st post.