AllocConsole与Visual Studio 2013

Question

I'm trying to have a console widow running alongside the main application window, apparently this should work and indeed the console window will show but the 3 lines of code starting with 'freopen' stop the compiling with errors such as "missing type specifier".

 #include <stdio.h>
 #include "Windows.h"
 #include "Wincon.h"

 BOOL f = AllocConsole();
 freopen("CONIN$", "r", stdin);
 freopen("CONOUT$", "w", stdout);
 freopen("CONOUT$", "w", stderr);

removing the 3 lines and replacing them with:

 OutputDebugString(L"\n");

as I think should be used to set the text in the window gives the following errors:

 1>main.cpp(13): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
 1>main.cpp(13): error C2365: 'OutputDebugStringW' : redefinition; previous definition was 'function'
 1>          C:\Program Files (x86)\Microsoft SDKs\Windows\v7.1A\include\winbase.h(7733) : see declaration of 'OutputDebugStringW'
 1>main.cpp(13): error C2440: 'initializing' : cannot convert from 'const wchar_t [2]' to 'int'
 1>          There is no context in which this conversion is possible

searching for an answer gives plenty of results but they generally say:

AllocConsole();
freopen("CONIN$", "r", stdin);
freopen("CONOUT$", "w", stdout);
freopen("CONOUT$", "w", stderr);

and that just is not working for me so what am I missing?

Answer 1

I personally use this in my programs that need a console and a gui.. You can try it and see if it works for you.. It uses the iostream 's instead of freopen .

It doesn't answer your question but it's an idea or another way of achieving the same goal.

#include <iostream>
#include <windows.h>
#include <fstream>
#include <streambuf>

class Console
{
    private:
        std::wstreambuf *CinBuffer, *CoutBuffer, *CerrBuffer;
        std::wfstream ConsoleInput, ConsoleOutput, ConsoleError;

    public:
        Console();
        Console(const Console &console) = delete;
        Console(Console&& console); = delete;
        ~Console();

        Console& operator = (const Console& other) = delete;
        Console& operator = (Console&& other) = delete;

        template<typename T>
        void operator << (const T &Data) {std::wcout<<Data<<std::flush;}
};


Console::Console()
{
    if (AllocConsole())
    {
        CinBuffer = std::wcin.rdbuf();
        CoutBuffer = std::wcout.rdbuf();
        CerrBuffer = std::wcerr.rdbuf();
        ConsoleInput.open("CONIN$", std::ios::in);
        ConsoleOutput.open("CONOUT$", std::ios::out);
        ConsoleError.open("CONOUT$", std::ios::out);
        std::wcin.rdbuf(ConsoleInput.rdbuf());
        std::wcout.rdbuf(ConsoleOutput.rdbuf());
        std::wcerr.rdbuf(ConsoleError.rdbuf());
    }
}

Console::~Console()
{
    ConsoleInput.close();
    ConsoleOutput.close();
    ConsoleError.close();
    std::wcin.rdbuf(CinBuffer);
    std::wcout.rdbuf(CoutBuffer);
    std::wcerr.rdbuf(CerrBuffer);
    FreeConsole();
}

Answer 2

I will try to answer your question by posting code that is exactly what you've posted, but add the appropriate #include files.

#include <windows.h>
#include <cstdio>

int main()
{
    BOOL f = AllocConsole();
    freopen("CONIN$", "r", stdin);
    freopen("CONOUT$", "w", stdout);
    freopen("CONOUT$", "w", stderr);
}

Using Visual Studio 2013, there are warnings concerning "dangerous function", but the code compiles successfully. Therefore you should take the code above as-is and compile it. If there are errors, please update your question.

---

Edit: Since you updated your question, the only reason I can see for those errors is because that code has to be within a function block. You can't have executable lines of code just sitting by themselves like that.

This is in essence what you posted:

#include <windows.h>
#include <cstdio>

BOOL f = AllocConsole();
freopen("CONIN$", "r", stdin);
freopen("CONOUT$", "w", stdout);
freopen("CONOUT$", "w", stderr);

This will not compile successfully due to the reasons above. The errors I get are similar to your errors.