strcat c++ ERROR

[RuWex]

class y{
   public:
          void func(QString )
          
   private:
         QString w;
}
void y:: func(QString x)
{ 
       strcat(w,x)
}
          

but I have an error:
no matching function for call 'strcat'
do you understand my problem?
thank:)

[jsulm]

@RuWex strcat has no idea what QString is. Please take a closer look at what parameters strcat takes...

[RuWex]

@jsulm char *....:(
how can I convert QString to char *?

[JonB]

@RuWex
Why would you want to? I strongly suspect you do want or need to call strcat() in any form, so why pursue that? You can append to QStrings: QString &QString::append(const QString &str). If you try to turn it into a char * to use with strcat(), my guess is you have not understood that you would not have the storage area you would need to strcat() onto it.

[jsulm]

@RuWex It's all in the documentation.
Depending on used encoding you can use https://doc.qt.io/qt-6/qstring.html#toLatin1 for example.

But why do you need strcat to concatenate two QStrings?!

[RuWex]

@jsulm @JonB
I need if for example I get in x="world"
and in W I have W= "hello"
I want to get W="hello world"
can I instead do W+=x?

[jsulm]

@RuWex Again: the answer is in the documentation which you really should use.

QString &	operator+=(const QString &other)
QString &	operator+=(QChar ch)
QString &	operator+=(QStringView str)
QString &	operator+=(QLatin1StringView str)
QString &	operator+=(const char *str)
QString &	operator+=(const QByteArray &ba)

[JonB]

@RuWex
Trust us, you don't want to use strcat()! :) Nor any of those C string functions like strcpy() etc., the C++/Qt world has moved on since then.

Start learning to use QString and its operators, much easier and safer.

[KroMignon]

@RuWex said in strcat c++ ERROR:

how can I convert QString to char *?

Please don't use try to program in C++ as you would do it with a C compiler!
This is a nonsense!

QString is a C++ class which includes all you need for string manipulation. All memory allocation will be handled internally by QString, even to string type (unicode, UTF-8, etc.) is taken in account.

If you use strcat(), you will have to take care about memory allocation/deallocation yourself. This will be error-prone and much more complex to code.

Why do you want doing this, when you are working is QString???