Undefined reference in G++.

[Andrix]

Hi!

I'm writing a class that have a static function

class Servicios {
public:
static String * intToString(int value);
};

an another class String that I write to.

namespace DataTypes {
class String {
......
};

ostream& operator<< (ostream&, const String &);
istream& operator>>(istream&, String &)
}

the class String has two iostream functions implemented outside the
class.

I have to a main.cc that has something like this:

int main() {
String * str = Servicios::intToString(100);
cout << str;

}

but when I do a make from all this, I have the error

In main.cc: undefined reference to .............function
ostream....(....)


Questions:
what is undefined reference? when ocurr? how to solve this problem?

thanks a lot.

Andrix.

 

[red floyd]

Hi!

I'm writing a class that have a static function

class Servicios {
public:
static String * intToString(int value);
};

an another class String that I write to.

namespace DataTypes {
class String {
......
};

ostream& operator<< (ostream&, const String &);
istream& operator>>(istream&, String &)
}

the class String has two iostream functions implemented outside the
class.

I have to a main.cc that has something like this:

int main() {
String * str = Servicios::intToString(100);
cout << str;

}

but when I do a make from all this, I have the error

In main.cc: undefined reference to .............function
ostream....(....)


Questions:
what is undefined reference? when ocurr? how to solve this problem?

You're trying to invoke operator<<(ostream&, const String *). It's not
defined anywhere. Why are you returing a String* from intToString,
rather than a String?

 

[Alf P. Steinbach]

* Andrix:

I'm writing a class that have a static function

class Servicios {
public:
static String * intToString(int value);
};

Who is responsible for deallocating that String, and how?

Better use std::string.

an another class String that I write to.

namespace DataTypes {
class String {
......
};

ostream& operator<< (ostream&, const String &);
istream& operator>>(istream&, String &)
}

the class String has two iostream functions implemented outside the
class.

I have to a main.cc that has something like this:

int main() {
String * str = Servicios::intToString(100);
cout << str;

That will output a pointer value.

}

but when I do a make from all this, I have the error

In main.cc: undefined reference to .............function
ostream....(....)


Questions:
what is undefined reference?

That your program is using something that is not defined.

when ocurr?

You haven't shown the relevant code.

how to solve this problem?

Define whatever is missing.

 

[Alf P. Steinbach]

* red floyd:

You're trying to invoke operator<<(ostream&, const String *).

Output of void* is defined. Nothing in the code shown indicates that
operator<<(ostream&, const String*) is invoked. We don't know what the
missing function is because the OP has replaced all info with periods.

 

[red floyd]

* red floyd:

Output of void* is defined. Nothing in the code shown indicates that
operator<<(ostream&, const String*) is invoked. We don't know what the
missing function is because the OP has replaced all info with periods.

Crud. Forgot about the automatic conversion to void*.