QProcess.execute（）一个DOS命令

Question

I'am trying to call a DOS command: subst with QProcess :

 QProcess process;
    int returnCode=process.execute(QString("subst " + DLetter+"  "+mountPath));
    qDebug()<<"returnCode"<<returnCode;
    if (returnCode==0){
        qDebug()<<"Mount "<<QString("subst " + DLetter+"  "+mountPath)
                <<"error"<<process.errorString()<<"id"<<process.pid();
        process.waitForFinished();
        ...
    }else
        qDebug()<<" mounting folder failed  "<<process.errorString();

My questions are : Is it enough to call execute() and waitForFinished() ? am I safe with calling execute() instead of start ? because I had issues with start() : it didn't work in all cases(it worked for mounting and didn't for dismounting folder) .

Any help wil be appreciated.

Answer 1

From the documentation of QProcess::execute() at http://doc.qt.digia.com/qt/qprocess.html#execute

you should do this:

int returnCode=process::execute(QString("subst " + DLetter+"  "+mountPath));
qDebug()<<"returnCode"<<returnCode;
if (returnCode==0){
    qDebug()<<"Mount "<<QString("subst " + DLetter+"  "+mountPath)
            <<"error"<<process.errorString()<<"id"<<process.pid();
}else
    qDebug()<<" mounting folder failed  ";

The key is QProcess::execute is a static member function that starts the program, waits for it to finish then returns the exit code of the process.

Note: I had to remove the non static calls to process.waitForFinished() and process.errorString() since neither can work from a static QProcess::execute.

Answer 2

If you are trying to call a DOS function, try to call it using the

#include <process.h>
...
system( "dir c:\\temp > c:\\temp\\output.txt" );

but this is now outdated. Try using

int nRet= (int)ShellExecute( 0,"open","calc.exe",0,0,SW_SHOWNORMAL);
if ( nRet <= 32 )
{
        DWORD dw= GetLastError(); 
        char szMsg[250];
        FormatMessage(
            FORMAT_MESSAGE_FROM_SYSTEM, 
            0, dw, 0,
            szMsg, sizeof(szMsg),
            NULL 
        );
        MessageBox( szMsg, "Error launching Calculator" );
}

Refer http://msdn.microsoft.com/en-us/library/windows/desktop/bb762153(v=vs.85).aspx to see how to use this function.