I am still kinda bad in c so pls dont mind my bad code or my missing knowledge. The project is about chosing a file and the paste it in the console for the user to read and i thought the best way would be using a dialog window (and i get more practice using the winapi).

Here my code for the window:

OPENFILENAMEA NameOfFile;
    ZeroMemory(&NameOfFile, sizeof(NameOfFile));
    NameOfFile.nFileOffset = 1;
    char szFile[260];
    NameOfFile.lpstrFile[0] = '\0';
    NameOfFile.lpstrFile = szFile;
    NameOfFile.nMaxFile = 4096;
    NameOfFile.Flags = OFN_ALLOWMULTISELECT;
    if (GetOpenFileName(&NameOfFile)) {
        
        cout << "opened";
    }

Now the wierd thing. The Programm crashes with the error "-1073741819". Google said its an access violation of smth (no clue what exactly it means).

When i comment out the ZeroMemory function i got a linker and compiler error that NameOfFile is apparently not initialized??? (but if its not commented it compiles normally?!)

CodePudding user response：

There are several issues in your code:

1. You need to set the lStructSize field of your OPENFILENAMEA variable.
2. You need to swap the 2 lines setting NameOfFile.lpstrFile, so that the pointer that you access (in order to write the zero termination) will point to a valid buffer.
3. NameOfFile.nMaxFile should be set to the size of the filename pointer by lpstrFile, i.e. the sizeof(szFile).

Fixed version:

OPENFILENAMEA NameOfFile;
ZeroMemory(&NameOfFile, sizeof(NameOfFile));
NameOfFile.lStructSize = sizeof(NameOfFile);   // Item 1 above
char szFile[260];
NameOfFile.lpstrFile = szFile;                 // Item 2 above
NameOfFile.lpstrFile[0] = '\0';                // Item 2 above 
NameOfFile.nMaxFile = sizeof(szFile);          // Item 3 above
NameOfFile.Flags = OFN_ALLOWMULTISELECT;
if (GetOpenFileName(&NameOfFile)) 
{
    std::cout << "opened";
}

For additional info you can see the example in the MS documentation here under the "Opening a File" section.

A side note: better to avoid using namespace std - see here Why is "using namespace std;" considered bad practice?.