CODEWITHSUNDEEP
c++stringclassconstructor
krispet krispet
krispet krispet

Reputation: 1678

c++ no matching constructor?

I have to create an own string class for a university project, my code so far looks like(I only show the relevant parts):

class SuchString
{
    char* str;
    size_t siz;
public:
    SuchString(char* a);
    ~SuchString();
    SuchString(SuchString& a);
    SuchString operator+(const SuchString& a) const;
    ...
    ...
};

As you can see I have a constructor for char* types, implemented as:

SuchString::SuchString(char* a)
{
    siz = strlen(a);
    str = new char[siz];
    strcpy(str, a);
}

The problem is with my operator+ function:

SuchString SuchString::operator+(const SuchString &a) const
{
    return SuchString(strcat(str, a.str));
}

I get the following error message:

No matching constructor for initialization of 'SuchString'

As far my understanding goes, the strcat function should return with a char*, and I have a constructor for that type.

I get the same error message for the following:

SuchString SuchString::operator+(const SuchString &a) const
{
    char* lel = strcat(str, a.str);
    return SuchString(lel);
}

And again, the same thing happens. I expected that the code SuchString(lel) would create a temporary variable, so the function can return with it, just as in the previous example.

Any help is appreciated.

ps: I know it's absolute nonsense to create a string class like this, but this is some small project for university.

Upvotes: 1

Views: 357

Answers (1)

Luchian Grigore
Luchian Grigore

Reputation: 258678

SuchString(SuchString& a); takes a non-const reference as a parameter, so passing it temporaries is not doable. What you probably want is

SuchString(const SuchString& a);

because when you return by value, a copy is made - i.e.:

return SuchString(lel);

will create a temporary SuchString which is then copied and returned. In theory, that is, because in practice the copy is most likely optimized out.

Upvotes: 3

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