Convert a double to a QString

Question

I am writing a program in QT. I want to convert a double into a Qstring in C++.

Answer 1

Building on @Kristian's answer, I had a desire to display a fixed number of decimal places. That can be accomplished with other arguments in the QString::number(...) function. For instance, I wanted 3 decimal places:

double value = 34.0495834;
QString strValue = QString::number(value, 'f', 3);
// strValue == "34.050"

The 'f' specifies decimal format notation (more info here, you can also specify scientific notation) and the 3 specifies the precision (number of decimal places). Probably already linked in other answers, but more info about the QString::number function can be found here in the QString documentation

Answer 2

Instead of QString::number() i would use QLocale::toString(), so i can get locale aware group seperatores like german "1.234.567,89".

Answer 3

You can use arg(), as follow:

double dbl = 0.25874601;
QString str = QString("%1").arg(dbl);

This overcomes the problem of: "Fixed precision" at the other functions like: setNum() and number(), which will generate random numbers to complete the defined precision

Answer 4

Check out the documentation

Quote:

QString provides many functions for converting numbers into strings and strings into numbers. See the arg() functions, the setNum() functions, the number() static functions, and the toInt(), toDouble(), and similar functions.

Answer 5

Use QString's number method (docs are here):

double valueAsDouble = 1.2;
QString valueAsString = QString::number(valueAsDouble);