使用Qt时如何打印到控制台

问题描述

我正在使用 Qt4 和 C++ 来制作一些计算机图形程序.我需要能够在运行时在我的控制台中打印一些变量，而不是调试，但是即使我添加了库，cout 似乎也不起作用.有没有办法做到这一点?

I'm using Qt4 and C++ for making some programs in computer graphics. I need to be able to print some variables in my console at run-time, not debugging, but cout doesn't seem to work even if I add the libraries. Is there a way to do this?

推荐答案

如果打印到 stderr 足够好，您可以使用以下最初用于调试的流:

If it is good enough to print to stderr, you can use the following streams originally intended for debugging:

#include<QDebug>

//qInfo is qt5.5+ only.
qInfo() << "C++ Style Info Message";
qInfo( "C Style Info Message" );

qDebug() << "C++ Style Debug Message";
qDebug( "C Style Debug Message" );

qWarning() << "C++ Style Warning Message";
qWarning( "C Style Warning Message" );

qCritical() << "C++ Style Critical Error Message";
qCritical( "C Style Critical Error Message" );

// qFatal does not have a C++ style method.
qFatal( "C Style Fatal Error Message" );

尽管如评论中所指出的，请记住，如果定义了 QT_NO_DEBUG_OUTPUT，则会删除 qDebug 消息

Though as pointed out in the comments, bear in mind qDebug messages are removed if QT_NO_DEBUG_OUTPUT is defined

如果你需要标准输出，你可以尝试这样的事情(正如凯尔斯特兰德指出的那样):

If you need stdout you could try something like this (as Kyle Strand has pointed out):

QTextStream& qStdOut()
{
    static QTextStream ts( stdout );
    return ts;
}

然后您可以按如下方式调用:

You could then call as follows:

qStdOut() << "std out!";

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