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Sergio Ramos
Asked: 2020-10-12 13:05:39 +0800 CST 2020-10-12 13:05:39 +0800 CST

Convert QString to char

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How do you convert a QStringto char? some easy and understandable way?

It is to understand it better thank you.

c++

3 Answers

  1. Best Answer

    QStringhas the method toStdString()that returns a std::string. Getting a charfrom this object is trivial:

    QString cadena = "Hola";
std::string cadenaStd = cadena.toStdString();
char c = cadenaStd[0];
std::cout << c;

    All the best.

    • 4

  2. Ask.

    How do you convert a QStringto char?

    There is no possible conversion from a complex type (in this case QString) to a fundamental type (in this case char), your question is similar to " How do you turn a Car into a Piston ? ".

    While it is true that Cars have engines and engines have Pistons, a Piston is a part of the Car.

    You can't turn a Car into a Piston although you will use Pistons to build your Car... parallelly you can't turn a QStringinto a charalthough you will use charas a part of a QString.

    So I guess you actually meant to ask:

    How do I access those charof a QString?

    So I'm going to base my answer on that assumption.

    Clarification.

    QStringit is created as a class analogous to the string class ; so it has similar, equivalent or exactly the same methods.

    Suggestion.

    Use the indexing operator (access via square brackets [and ]). Given the almost complete equivalence between QStringand std::stringboth objects have this operator and it is used in the same way.

    So, in the following example, they both show @using the bracket operator on the fifth position:

    QString       q_mail("[email protected]");
std::string stl_mail("[email protected]");

std::cout << "quinto caracter: " <<   q_mail[4];
std::cout << "quinto caracter: " << stl_mail[4];
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  3. Well, assuming you're using Qt 5.x, it's relatively simple.

    To convert one to one (or some) of the characters in a QStringyou would have to use something like the following code:

     QString ejemplo="ejemplo";
 std::cout << ejemplo.at(0).toLatin1(); //funcion at devuelve el tipo de dato Qchar de la cadena en la posicion 0
 //y .toLatin1() devuelve el caracter en dato char.

    Instead if you want to convert the whole QString, a faster option is to use .toLatin1()on the object QString.

     QString ejemplo2="ejemplo2";
 ejemplo2.toLatin1(); //esta funcion devuelve un QByteArray

    A QByteArrayis roughly a class that serves as a dynamic array char(you can concatenate, add, remove, etc.), without the complexity of dynamic memory.

    In addition, it must be said that QByteArrayyou can obtain the data as a type charif you use the dataor functions constData.

     QByteArray ejemploByteArray=ejemplo2.toLatin1();
 ejemploByteArray.constData(); //devuelve un puntero constante a un data *char, por ejemplo si solo es un parametro de lectura
 ejemploByteArray.data(); //devuelve un puntero  *char, este si modificable, por lo que si lo manipulas cambiaras tambien los datos de QByteArray, por lo que aqui si hay que tener cuidado.
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