I am trying to add a choose file dialog box to my project which now can only take the filename input by the user.
I did some search and it seems windows API with GetOpenFileName function is the easiest way for me to do that. However, when I copy&paste the example code whether from MSDN or other websites, I got some build errors.
I am using visual studio 2017. And the example code I used is from http://www.cplusplus.com/forum/windows/169960/:
#include <iostream>
#ifndef NOMINMAX
#define NOMINMAX
#endif
#include <windows.h>
int main()
{
char filename[ MAX_PATH ];
OPENFILENAME ofn;
ZeroMemory( &filename, sizeof( filename ) );
ZeroMemory( &ofn, sizeof( ofn ) );
ofn.lStructSize = sizeof( ofn );
ofn.hwndOwner = NULL; // If you have a window to center over, put its HANDLE here
ofn.lpstrFilter = "Text Files\0*.txt\0Any File\0*.*\0";
ofn.lpstrFile = filename;
ofn.nMaxFile = MAX_PATH;
ofn.lpstrTitle = "Select a File, yo!";
ofn.Flags = OFN_DONTADDTORECENT | OFN_FILEMUSTEXIST;
if (GetOpenFileNameA( &ofn ))
{
std::cout << "You chose the file \"" << filename << "\"\n";
}
else
{
// All this stuff below is to tell you exactly how you messed up above.
// Once you've got that fixed, you can often (not always!) reduce it to a 'user cancelled' assumption.
switch (CommDlgExtendedError())
{
case CDERR_DIALOGFAILURE : std::cout << "CDERR_DIALOGFAILURE\n"; break;
case CDERR_FINDRESFAILURE : std::cout << "CDERR_FINDRESFAILURE\n"; break;
case CDERR_INITIALIZATION : std::cout << "CDERR_INITIALIZATION\n"; break;
case CDERR_LOADRESFAILURE : std::cout << "CDERR_LOADRESFAILURE\n"; break;
case CDERR_LOADSTRFAILURE : std::cout << "CDERR_LOADSTRFAILURE\n"; break;
case CDERR_LOCKRESFAILURE : std::cout << "CDERR_LOCKRESFAILURE\n"; break;
case CDERR_MEMALLOCFAILURE : std::cout << "CDERR_MEMALLOCFAILURE\n"; break;
case CDERR_MEMLOCKFAILURE : std::cout << "CDERR_MEMLOCKFAILURE\n"; break;
case CDERR_NOHINSTANCE : std::cout << "CDERR_NOHINSTANCE\n"; break;
case CDERR_NOHOOK : std::cout << "CDERR_NOHOOK\n"; break;
case CDERR_NOTEMPLATE : std::cout << "CDERR_NOTEMPLATE\n"; break;
case CDERR_STRUCTSIZE : std::cout << "CDERR_STRUCTSIZE\n"; break;
case FNERR_BUFFERTOOSMALL : std::cout << "FNERR_BUFFERTOOSMALL\n"; break;
case FNERR_INVALIDFILENAME : std::cout << "FNERR_INVALIDFILENAME\n"; break;
case FNERR_SUBCLASSFAILURE : std::cout << "FNERR_SUBCLASSFAILURE\n"; break;
default : std::cout << "You cancelled.\n";
}
}
}
When I copy&paste to vs, it shows the following:
Severity Code Description Project File Line Suppression State
Error C2440 '=': cannot convert from 'char [260]' to 'LPWSTR' ConsoleApplication1 c:\users\xfan0\documents\visual studio 2017\projects\consoleapplication1\consoleapplication1\consoleapplication1.cpp 18
Severity Code Description Project File Line Suppression State
Error C2440 '=': cannot convert from 'const char [19]' to 'LPCWSTR' ConsoleApplication1 c:\users\xfan0\documents\visual studio 2017\projects\consoleapplication1\consoleapplication1\consoleapplication1.cpp 20
Severity Code Description Project File Line Suppression State
Error C2664 'BOOL GetOpenFileNameA(LPOPENFILENAMEA)': cannot convert argument 1 from 'OPENFILENAME *' to 'LPOPENFILENAMEA' ConsoleApplication1 c:\users\xfan0\documents\visual studio 2017\projects\consoleapplication1\consoleapplication1\consoleapplication1.cpp 23
Severity Code Description Project File Line Suppression State
Error (active) E0167 argument of type "OPENFILENAME *" is incompatible with parameter of type "LPOPENFILENAMEA" ConsoleApplication1 c:\Users\XFAN0\Documents\Visual Studio 2017\Projects\ConsoleApplication1\ConsoleApplication1\ConsoleApplication1.cpp 23
Tried to search for that but had not found my luck :(
The method Microsoft normally advocates is to use their "generic text" macros, so your string literals would look like this:
ofn.lpstrFilter = _T("Text Files\0*.txt\0Any File\0*.*\0");
ofn.lpstrTitle = _T("Select a File, yo!");
This way, you can build for narrow or wide character strings (the latter by defining UNICODE and _UNICODE). The _T will map to nothing for a narrow-character build, and to a L for a wide-character build, so you automatically get the right kind of string for the way you're building.
To use this, you include <tchar.h>.
For example:
#include <iostream>
#include <tchar.h>
#ifndef NOMINMAX
#define NOMINMAX
#endif
#include <windows.h>
int main()
{
char filename[ MAX_PATH ];
OPENFILENAME ofn;
ZeroMemory( &filename, sizeof( filename ) );
ZeroMemory( &ofn, sizeof( ofn ) );
ofn.lStructSize = sizeof( ofn );
ofn.hwndOwner = NULL; // If you have a window to center over, put its HANDLE here
ofn.lpstrFilter = _T("Text Files\0*.txt\0Any File\0*.*\0");
ofn.lpstrFile = filename;
ofn.nMaxFile = MAX_PATH;
ofn.lpstrTitle = _T("Select a File, yo!");
ofn.Flags = OFN_DONTADDTORECENT | OFN_FILEMUSTEXIST;
if (GetOpenFileName( &ofn ))
{
std::cout << "You chose the file \"" << filename << "\"\n";
}
else
{
// All this stuff below is to tell you exactly how you messed up above.
// Once you've got that fixed, you can often (not always!) reduce it to a 'user cancelled' assumption.
switch (CommDlgExtendedError())
{
case CDERR_DIALOGFAILURE : std::cout << "CDERR_DIALOGFAILURE\n"; break;
case CDERR_FINDRESFAILURE : std::cout << "CDERR_FINDRESFAILURE\n"; break;
case CDERR_INITIALIZATION : std::cout << "CDERR_INITIALIZATION\n"; break;
case CDERR_LOADRESFAILURE : std::cout << "CDERR_LOADRESFAILURE\n"; break;
case CDERR_LOADSTRFAILURE : std::cout << "CDERR_LOADSTRFAILURE\n"; break;
case CDERR_LOCKRESFAILURE : std::cout << "CDERR_LOCKRESFAILURE\n"; break;
case CDERR_MEMALLOCFAILURE : std::cout << "CDERR_MEMALLOCFAILURE\n"; break;
case CDERR_MEMLOCKFAILURE : std::cout << "CDERR_MEMLOCKFAILURE\n"; break;
case CDERR_NOHINSTANCE : std::cout << "CDERR_NOHINSTANCE\n"; break;
case CDERR_NOHOOK : std::cout << "CDERR_NOHOOK\n"; break;
case CDERR_NOTEMPLATE : std::cout << "CDERR_NOTEMPLATE\n"; break;
case CDERR_STRUCTSIZE : std::cout << "CDERR_STRUCTSIZE\n"; break;
case FNERR_BUFFERTOOSMALL : std::cout << "FNERR_BUFFERTOOSMALL\n"; break;
case FNERR_INVALIDFILENAME : std::cout << "FNERR_INVALIDFILENAME\n"; break;
case FNERR_SUBCLASSFAILURE : std::cout << "FNERR_SUBCLASSFAILURE\n"; break;
default : std::cout << "You cancelled.\n";
}
}
}
To get a "save" filename instead, just change the GetOpenFilename to GetSaveFilename. There are a few differences in the flags you're likely to pass in the OPENFILENAME though--for example, it's pretty common to pass OFN_FILEMUSTEXIST when you're opening a file, but you almost never want to when you're saving a file.