Convert QString to char

QString has the toStdString() method that returns a std::string . Obtaining a char from this object is trivial:

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

Greetings.

Question.

  

How do you convert a QString to char ?

There is no possible conversion of a complex type (in this case QString ) to a fundamental type (in this case char ), your question is similar to " How does a Coche in a Piston ? ".

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

You can not convert a Car into a Piston although you will use Pistons to build your Car ... parallel you can not convert a QString into a char although you will use char as a piece of QString .

So I guess you really wanted to ask:

  

How do I access the char of a QString ?

So I will base my answer on that assumption.

Clarification.

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

Suggestion.

Use the index operator (access by square brackets [ and ] ). Given the almost complete equivalence between QString and std::string both objects have that operator and is used in the same way.

• QString::operator [] .
• std::string::operator [] .

So, in the following example, both show @ when using the    operator brackets 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];

Well, assuming you use Qt 5.x, it's relatively simple.

To convert one to one (or some) of the characters of a QString you should 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.

On the other hand, if you want to convert all the QString , a faster option is to use .toLatin1() on the object QString .

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

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

Also it must be said that from a QByteArray you can get the data as type char if you use the functions data or 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.