How to parse an command line argument string into a QStringList for QProcess ?

[lansing]

I have a command line string that I want to run with QProcess, it was used to be like this:

QString executable = "x264.exe";
QString arguments= " -i xxxxx -o test.mp4";
QString commandline = executable + arguments;
process->start(commandline);

But now qt warns about this syntax being deprecated, so how do update this and turn the arguments string into QStringList?

[JonB]

@lansing
In this case you would be far better generating the list of separate arguments which QProcess::start() wants, rather than making a string as you do now.

QString executable = "x264.exe";
QStringList arguments =  (QStringList() << "-i" << "xxxx" << "-o" << "test.mp4");
process->start(executable, arguments);

[lansing]

@JonB

The command line will be entered by the users.

[mrjj]

@lansing
Hi
And how does the user enter them ?

I mean via some GUI or via actual command line parameters to your app`?

[lansing]

@mrjj

I have a gui with a textarea for the entry

[mrjj]

@lansing
ok so user type one parameter pr line or does it come
like par1=1 par2=2 on same line ?

So we need to find way to split it into elements and
often we can split on space or or new line.

[lansing]

@mrjj

The commandline will be entered by the user in one line, without the executable at the start of the line.

-i xxxxx -o "D:\my test.mp4"

I tried splitting it by space but it failed when I included a file path.

[mrjj]

@lansing
Why not just use multiple LineEdits?

Input:   [              ]
output:[              ]

and then add -i and -o yourself when you build the QStringList

[lansing]

@mrjj

I think you're right, separating input/output file path from the argument string will resolve headache like this. Then the argument string can be easily splitted by space and put into a QStringList.

[Chris Kawa]

There's also QCommandLineParser class that can take care of all the spacing, quoting and parsing problems for you.

[JonB]

@lansing said in How to parse an command line argument string into a QStringList for QProcess ?:

The commandline will be entered by the user in one line

Then instead of using the deprecated QProcess::start() which accepted a string you will want to use the new [static]QStringList QProcess::splitCommand(QStringView command), which effectively exposes the function to do the splitting into arguments that the old start() used to offer.

[lansing]

@JonB

Thanks it worked like magic.

QString executable = "x264.exe";
QString arguments = " -i xxxxx -o test.mp4";
QStringList argumentsList =  QProcess::splitCommand(arguments);
process->start(executable, argumentsList );