Find exact match for substring in a QString using QRegularExpression

[MarKS]

I woud like to find exact match of a substring from QString. For instance, i have a file like something_plugin32.dll and
something_plugin32d.dll in a directory and i would like to load appropriate plugin based on current Debug/Release configuration.

I did something like this:

#ifdef NDEBUG
    QRegularExpression regEx("_plugin32");
#endif

#ifdef _DEBUG
    QRegularExpression regEx("_plugin32d");
#endif

and i try to find all plugins with suffix _plugin32 or _plugin32d

while (directoryIterator.hasNext())
{
    QString fileName = directoryIterator.fileName();
    QRegularExpressionMatch expMatch = regEx.match(fileName, 0, 
                                                            QRegularExpression::PartialPreferCompleteMatch);  
    if (expMatch.hasMatch())
    {
          // In release configuration
          // lists out all the plugins containing "_plugin32" including debug versions
          qInfo() << "Plugin" << fileName << "found";
    }
}

I am not so familiar with regular expressions in general, may be my patterns are set wrong.

[KroMignon]

@MarKS said in Find exact match for substring in a QString using QRegularExpression:

tried QString::contains() but have the same issue. Any simpler way to achieve this?

Sometimes the simplest solution are the best:

#ifdef DEBUG
     QString pattern("_plugin32d");
#else
     QString pattern("_plugin32");
#endif
QDir path("the directory");
path.setFilter(QDir::Files);
for(const auto& file : path.entryInfoList(QStringList() << "*.dll"))
{
    if(file.baseName().endsWidth(pattern))
        qInfo() << "Plugin" << file.fileName() << "found";
}

[Christian Ehrlicher]

Why do you need a regexp for this at all?

[MarKS]

@Christian-Ehrlicher tried QString::contains() but have the same issue. Any simpler way to achieve this?

[KroMignon]

@MarKS said in Find exact match for substring in a QString using QRegularExpression:

tried QString::contains() but have the same issue. Any simpler way to achieve this?

Sometimes the simplest solution are the best:

#ifdef DEBUG
     QString pattern("_plugin32d");
#else
     QString pattern("_plugin32");
#endif
QDir path("the directory");
path.setFilter(QDir::Files);
for(const auto& file : path.entryInfoList(QStringList() << "*.dll"))
{
    if(file.baseName().endsWidth(pattern))
        qInfo() << "Plugin" << file.fileName() << "found";
}

[MarKS]

@KroMignon This is a nice way to address this issue. But i had additional criterions which i forgot to mention in the question like:
it must work for .so extensions as well and my directory has multiple subdirectories. But your answer provided me with sufficient idea to implement it myself. I implemented it something like this:

• To compare with substring i used endsWith(pattern)

• I used QDirIterator for iterating through files and subdirectories

#ifdef NDEBUG
    QString pattern("_plugin32");
#else
    QString pattern("_plugin32d");
#endif

while (directoryIterator.hasNext())
{
    // get the file name and remove extensions like .so or .dll
    QString fileName = directoryIterator.fileName().split('.')[0];

    if (fileName.endsWith(pattern))
    {
        qInfo() << "Plugin" << fileName << "found";            
    }
}

Thanks for the help!

[KroMignon]

@MarKS said in Find exact match for substring in a QString using QRegularExpression:

// get the file name and remove extensions like .so or .dll
QString fileName = directoryIterator.fileName().split('.')[0];

This could be simplified with QString fileName = directoryIterator.fileInfo().baseName();

[MarKS]

@KroMignon Indeed!