getting runtime error: "program.exe not a valid win32 application"

Question

I am relatively new to Windows programming and this forum. As the title says, I'm getting this error whenever I try to run a particular C program I wrote. The program is compiled as x64 running on a 64-bit machine. Edit: After I press the OK button on the popup, I get an "Access is denied" message. The code, which I don't think has anything to do with the problem follows:

// CrtFil2.cpp : Defines the entry point for the console application.
//


#include "stdafx.h"
#include "string.h"

//#include BasInc2.c
//#include FilMst2.c

FILE * Opn(char PthNam[], char OpnMod[]);


void main()
{
    FILE    * FilMstFilPtr = NULL;

    FilMstFilPtr = Opn("\\temp\\test.file", "wb");
    printf("filptr=0x%p\n", FilMstFilPtr);
    return;
}

//******************************************************************************
//  Open a file.
//******************************************************************************
FILE * Opn(char PthNam[], char OpnMod[])
{
    FILE    * FilPtr = NULL;

    errno = fopen_s(&FilPtr, PthNam, OpnMod);
    if (errno != 0) {
        printf("%s\n", PthNam);
        perror("Could not open file");
        return NULL;
    }
    printf("file opened for mode %s\n", OpnMod);
    return FilPtr;
}

I got the following output on my build:

1>------ Build started: Project: CrtFil2, Configuration: Debug x64 ------ 1> CrtFil2.cpp 1> CrtFil2.vcxproj -> C:\$SmpSysLib\$QsysS\CrtFil2\x64\Debug\CrtFil2.exe ========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========

This worked until about an hour ago. Then I commented some lines and it quit working. I looked through the first 50 answers supplied on a search, and most of them involved running on XP or a particular 3rd party .exe. If this is a duplicate question, please let me know. A couple suggestions I tried were to shut down Visual Studio and restart it, and also shutting and restarting the PC. One answer pointed to this link: https://superuser.com/questions/358434/how-to-check-if-a-binary-is-32-or-64-bit-on-windows. According to the answer, the .exe is compiled as a x86 application. However at the top of the VS display it says x64 as well as in the Property->Configuration Manager. This is on Visual Studio-2015 Community Edition Update 1.

I got the original program working even though the source code remained the same. But the same error cropped up on a different C program. I tried reinstalling VS but got an error when I tried to do it, so I'm somewhat stuck.

Is there a way to fix this problem?

Answer 1

this header file: #include "stdafx.h" is actually a composite compiled header of all the header files from that source file (and their dependencies).

If you were deleting #include statements during the editing, visual studio may have deleted that composite header file.

all the #include statements must be in the source file.

There are several ways to cause visual studio to delete that compiled header file. One way is to comment out the #include statements.

Answer 2

it is best to write portable code, even if only going to run on windows.

so strongly suggest writing your C functions like so:

#define _CRT_SECURE_NO_DEPRECATE
//#include "stdafx.h
#include <stdio.h>
#include <string.h>
#include <errno.h>


FILE * Opn(char PthNam[], char OpnMod[]);


int main( void )
{
    FILE    * FilMstFilPtr = NULL;

    FilMstFilPtr = Opn("\\temp\\test.file", "wb");
    printf("filptr=0x%p\n", (void*)FilMstFilPtr);
    return 0;
}

//*****************************************************************
//  Open a file.
//*****************************************************************
FILE * Opn(char PthNam[], char OpnMod[])
{
    FILE    * FilPtr = NULL;

    #if 0
    errno = fopen_s(&FilPtr, PthNam, OpnMod);
    if (errno != 0) {
        printf("%s\n", PthNam);
        perror("Could not open file");
        return NULL;
    }
    #else
    if( NULL == (FilPtr = fopen( PthNam, OpnMod ) ) )
    {
        fprintf( stderr, "fopen failed for %s with mode: %s due to: %s\n", 
                 PthNam, OpnMod, strerror( errno ) );
    }
    else
        printf("file opened for mode %s\n", OpnMod);
    #endif
    return FilPtr;
}