Thread: Compare integers with hard coded values goes wrong in dll

Woops. Forgot the C code in the first post. It was from one of the experiments. Here is the code as described:

Code:

int _stdcall spil(int *games, int *gameskifte)
{
            if (*games == 0){
                         if (*gameskifte == 1) return *games + 1;
                         else return *games + 2;}
            else{
                         if (*games < 3){
                                     if (*gameskifte == 1) return *games + 2;
                                     else return *games + 4;}
                         else{
                                     if (*gameskifte == 1) return *games + 3;
                                     else return *games + 5;
                         }
            }
 
                                     return 0;
}

That gives me games + 4 as a result

This code (where all compares are "<")

Code:

int _stdcall spil(int *games, int *gameskifte)
{
            if (*games < 1){
                         if (*gameskifte < 2) return *games + 1;
                         else return *games + 2;}
            else{
                         if (*games < 3){
                                     if (*gameskifte < 2) return *games + 2;
                                     else return *games + 4;}
                         else{
                                     if (*gameskifte < 2) return *games + 3;
                                     else return *games + 5;
                         }
            }
 
                                     return 0;
}

Always gives me games + 1

and

This code (where all compares are ">")

Code:

int _stdcall spil(int *games, int *gameskifte)
{
            if (*games > 1){
                         if (*gameskifte > 2) return *games + 1;
                         else return *games + 2;}
            else{
                         if (*games > 3){
                                     if (*gameskifte > 2) return *games + 2;
                                     else return *games + 4;}
                         else{
                                     if (*gameskifte > 2) return *games + 3;
                                     else return *games + 5;
                         }
            }
 
                                     return 0;
}

always gives me games + 5

So when doing the return calculation it knows the value of *games but when comparing *games to another hardcoded value it throws a false when doing a direct or ">" compare and a positive when doing any "<" compare no matter if the value is lower or higher.

First off, try a simple test like this.

Code:

#include <stdio.h>
#include <stdlib.h>

int spil(int *games, int *gameskifte)
{
  if (*games < 1) {
    if (*gameskifte < 2)
      return *games + 1;
    else
      return *games + 2;
  } else {
    if (*games < 3) {
      if (*gameskifte < 2)
        return *games + 2;
      else
        return *games + 4;
    } else {
      if (*gameskifte < 2)
        return *games + 3;
      else
        return *games + 5;
    }
  }

  return 0;
}


int main()
{
  int games,gameskifte;
  for ( games = 0 ; games < 5 ; games++ ) {
    for ( gameskifte = 0 ; gameskifte < 5 ; gameskifte++ ) {
      int result = spil(&games,&gameskifte);
      printf("games=%d, gameskifte=%d, result=%d\n", games, gameskifte, result);
    }
  }
  return 0;
}



$ gcc bar.c
$ ./a.out 
games=0, gameskifte=0, result=1
games=0, gameskifte=1, result=1
games=0, gameskifte=2, result=2
games=0, gameskifte=3, result=2
games=0, gameskifte=4, result=2
games=1, gameskifte=0, result=3
games=1, gameskifte=1, result=3
games=1, gameskifte=2, result=5
games=1, gameskifte=3, result=5
games=1, gameskifte=4, result=5
games=2, gameskifte=0, result=4
games=2, gameskifte=1, result=4
games=2, gameskifte=2, result=6
games=2, gameskifte=3, result=6
games=2, gameskifte=4, result=6
games=3, gameskifte=0, result=6
games=3, gameskifte=1, result=6
games=3, gameskifte=2, result=8
games=3, gameskifte=3, result=8
games=3, gameskifte=4, result=8
games=4, gameskifte=0, result=7
games=4, gameskifte=1, result=7
games=4, gameskifte=2, result=9
games=4, gameskifte=3, result=9
games=4, gameskifte=4, result=9

Next, put some debug print statements inside your C function (maybe even log to a file if you don't have a handy console), to verify what you're being passed makes sense.

> Private Declare Function game Lib "c:\users\musholm\documents\visual studio 2013\Projects\mitprojekt\Debug\mitprojekt.dll" (ByRef games As Integer, ByRef gameskifte As Integer) As Integer
But your function is called spil ?
How does that work?

Put this at the start of your C function.

Code:

  FILE *fp = fopen("gamesLog.txt","a");
  if ( fp ) {
    fprintf(fp,"games=%d, gameskifte=%d\n",*games,*gameskifte);
    fclose(fp);
  }

This will produce a text file (in the current directory of the executable) showing you what values you got.



> How do I perform the test you suggest? I have Visual Studio Express at my disposal.
You should be able to create a new project using a project wizard. If you select a "console" project, the rest should happen automatically.
Then all you do is copy/paste the source code into it.

You could make it link with your DLL for a proper test, but that's a little more involved than simple copy/paste.