Question

Using VS2012, I noticed that a switch that’s been working for several years now seems to be broken in Release builds but works correctly (or at least as it used to) in Debug builds. I can’t see anything at all wrong with the code so would appreciate some feedback on the correctness of using return statements from within a switch block.

The following code compiles ok but gives the wrong output in a Release build on Win7 32-bit…

#include <stdio.h>
#include <tchar.h>

class CSomeClass
{
public:
    float GetFloat(int nInt)
    {
        printf("GetFloat() - entered\n");
        switch (nInt)
        {
        case 1 :
            printf("GetFloat() - case 1 entered\n");
            return 0.5F;
        case 0 :
            printf("GetFloat() - case 0 entered\n");
            return 1.0F;
        case 2 :
            printf("GetFloat() - case 2 entered\n");
            return 2.0F;
        case 3 :
            printf("GetFloat() - case 3 entered\n");
            return 3.0F;
        case 4 :
            printf("GetFloat() - case 4 entered\n");
            return 4.0F;
        }
        printf("GetFloat() - exit\n");
        return 1.0F;
    }
};

int _tmain(int argc, _TCHAR* argv[])
{
    CSomeClass pClass;
    float fValue = pClass.GetFloat(3);
    printf("fValue = %f\n", fValue);

    return 0;
}

If you can repeat the problem, and have a MS Connect login, maybe you can vote it up here too?

Actual results

Release build gives the following incorrect result:

GetFloat() - entered
GetFloat() - case 3 entered
fValue = 0.000000

Expected results

Debug build gives the following correct result:

GetFloat() - entered
GetFloat() - case 3 entered
fValue = 3.000000

MS Connect bug report

Answer 1

It sounds like it might be this bug? Where there is a problem in returning floating point values generated in a similar way?