str[0] = 'a' => how to make it work (overloading operators)

[GaPe]

Hi!

I have a problem with overloading a [] operator. Whenever I want to assign value to a string I always get this message "error C2106: '=' : left operand must be l-value".

Example:
str[1] = 'a';

My code in .hpp file:

String &operator=(const String &secondString);
String &operator=(const char *secondString);
String &operator=(const char &character);
char operator[](int index);

Code in .cpp file:

String &String::operator=(const String &secondString) {
	setString(secondString);
	return *this;
}

String &String::operator=(const char *secondString) {
	setString(secondString);
	return *this;
}

String &String::operator=(const char &character) {
	setString(character);
	return *this;
}

char String::operator[](int index) {
	this->setIndex(index);
	return getChar(index);
}

So, what am I doing wrong?

[pianorain]

char& operator[](int index);

You need a reference for a l-value.

[7stud]

...otherwise your operator[] turns this statement:

a[1] = 'a';

into something like:

'b' = 'a';

which doesn't make any sense because 'b' isn't a variable. On the other hand, a reference to a char acts like a pointer to a specific location in memory, and you can assign a char to that memory.

[GaPe]

Thank you very much!