Qstring Arg

The subject of qstring arg encompasses a wide range of important elements. How to change string into QString? If compiled with STL compatibility, QString has a static method to convert a std::string to a QString: c++ - How to format a QString? I'd like to format a string for Qt label, I'm programming in C++ on Qt.

It's important to note that, in ObjC I would write something like: NSString *format=[NSString stringWithFormat: ... Furthermore, ]; How to do something like that in... get part of QString - Stack Overflow. I want to get QString from another QString, when I know necessary indexes. For example: Main string: "This is a string".

I want to create new QString from first 5 symbols and get "This ". How to convert QString to std::string? @eyllanesc the question text says "How to output the content of qstring into the console?" , it seems OP assumes converting to std::string is the only way. It's really two questions being asked at once . c++ - What's the purpose of QString? To stay consistent with this, I've been trying to accept and return QString from most of my function calls, however I find myself converting to and from std::string a lot to use most of the standard library facilities.

My question here is, what's the purpose of QString if std::string is part of the standard library? Building on this, c++ - How to convert int to QString? Is there a QString function which takes an int and outputs it as a QString? Whats the best way to send QStrings in a function call?.

Hence this is slower than passing a QString, especially if the QString parameter is much used. Similarly, i would recommend to always pass a const QString&, and if you need maximum speed on the called side, make a QString copy there, and access this local copy to avoid a double-indirection (faster, less generated code). Another key aspect involves, c++ - QString to char* conversion - Stack Overflow. QString does not use "char" internally so you'd end up with garbage (actually probably the first character on its own, possibly mojibaked as it's UTF-16 according to the docs) In general, reinterpret_cast<> is almost always wrong - it exists because sometimes it's necessary, but in the vast majority of cases, you're doing the wrong thing.

c++ - how to initialize a QString to null? Another key aspect involves, for historical reasons, QString distinguishes between a null string and an empty string. A null string is a string that is initialized using QString 's default constructor or by passing (const char *)0 to the constructor. An empty string is any string with size 0.

A null string is always empty, but an empty string isn't necessarily null: qt - Format QString with fixed number of digits - Stack Overflow. QString::arg You can specify the formatting with QString::arg like: %.3f: QString("%1").arg(1.3, 0, 'f', 3): where the second argument is the field-width (minimum width of the resulting string, 0 here), the third is the format of the number, (in this case f means use no scientific notation), and the fourth is the precision (3 number of decimal places).