Qt: Converting Text and Numbers to and from QString

× NOTE:   For examples of converting standard C++ strings to numbers, follow this link.

This page provides several examples of how to convert among QString objects, standard C++ strings, and numbers. Remember to include the necessary Qt class headers for QString and QLocale!

 

  • Convert a QString to a std::string:

    std::string myString = qtString.toStdString();

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  • Convert a std::string to a QString:

    std::string myString = “Do you like football?”;
    QString qtString = QString::fromStdString(myString);

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  • Convert a number to a QString: 

    int theAnswer = 42;
    QString qtString = QString::number(theAnswer);

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  • Convert a QString to an integer: 

    QString myString = "42";
    int theAnswer = myString.toInt();

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  • Convert a QString to a double: 

    QString gpaString = "3.75";
    double gpa = gpaString.toDouble();

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  • Convert a number to a QString, and format it to two decimal places: 

    double price = 89.0278;
    QString qtString = QString().asprintf("%0.2f", price);   // 89.03

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  • Convert a number to a QString, and format it to two decimal places with a leading + sign 

    double changeInPrice = 1.25;
    QString qtString = QString().asprintf("%+0.2f", changeInPrice);   // +1.25

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  • Convert a number to a QString, and format it with comma separators

    int volume = 37800900;
    QString qtString = QLocale(QLocale::English).toString(volume);   // 37,800,900