Printf to stream

MartinD

Hello,
I have this function:

void app_trace_log(const char * format, ... ) {
//qDebug() << ???????????;
}

The format argument uses printf like syntax for printing variable number of arguments (...). What's the easiest way to transform it to qt stream output (like qDebug())?

SGaist

Hi,

You could use QString::asprintf (new in 5.5) or QTextStream

Hope it helps

? Offline

@SGaist How would you use QTextStream for this? The only solution I know goes like:

void app_trace_log(const char *format, ...) {
    va_list args;
    va_start(args, format);
    char *result;
    const int n = vasprintf(&result, format, args);
    va_end(args);
    if (n>=0) {
        qDebug() << result;
        free(result);
    }
}

SGaist

Sorry, I didn't meant it as drop-in replacement.

Thanks for the example.

Note that I'd rather recommend the use of QLoggingCategory for that kind of task.