C++ win32控制台应用程序使用Windows API添加“选择文件”对话框

Question

我想添加一个选择文件对话框到我的项目，现在只能由用户输入文件名。

我做了一些搜索，它似乎Windows API与GetOpenFileName函数是我这样做的最简单的方法。但是，当我复制&粘贴示例代码无论是从MSDN或其他网站，我有一些构建错误。

我使用的Visual Studio 2017而我使用的示例代码是从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"; 
    } 
    } 
} 

当我&复制粘贴到VS，它显示以下内容：

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 

试过搜索但没有找到我的运气:(

Answer 1

微软通常提倡的方法是使用他们的“通用文本”宏，所以你的st环文字是这样的：

ofn.lpstrFilter = _T("Text Files\0*.txt\0Any File\0*.*\0"); 
ofn.lpstrTitle = _T("Select a File, yo!"); 

这样，您就可以建立窄或宽字符串（后者通过定义UNICODE和_UNICODE）。 _T将映射为窄字符版本的任何内容，对于宽字体版本则不会映射到L，因此您可以根据自己的创建方式自动获取正确类型的字符串。

要使用此功能，请包括<tchar.h>。

例如：

#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"; 
    } 
    } 
} 

为了得到一个 “保存” 名而不是，只是改变了GetOpenFilename到GetSaveFilename。虽然在OPENFILENAME中可能会传递的标志存在一些差异 - 例如，在打开文件时通过OFN_FILEMUSTEXIST很常见，但几乎从不想在保存文件时。