Attempting My String Class

[Technocrat]

Ok I have the suggestion that Zaei and Cornedbee gave me to use an inherted template, and I have added one of my functions to it to test it out. This is what I have so far:

template<typename C, typename T = std::char_traits<C>, typename A = std::allocator<C> >
class TECHSTRING_CL : public std::basic_string<C, T, A>
{
public:
	bool IsNumeric()
	{
		/*>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>*/
		const string	_DIGITS_C	= "1234567890.";		//Const String To Hold The Values Wanted
		int				_iRet		= 0;					//Temp Return VAR
		/*<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<*/
		
		if(this->length() <= 0)							//If A Bad Or Empty String Is Passed
			return false;									//Return False

		_iRet = this->find_first_not_of(_DIGITS_C);		//Make Sure Everything Is There
		
		return (_iRet == -1);								//If The String Is Numeric _iRet = -1
	};
};

typedef TECHSTRING_CL<char> TechString;
TechString s;

But when I do the following:
s = "123456";

I get:
error C2679: binary '=' : no operator found which takes a right-hand operand of type 'const char [7]' (or there is no acceptable conversion)

So whats up?

[CornedBee]

There are a few things that aren't properly inherited. Those are the constructors and the assignment operators (including combined assignment like +=), you have to rewrite these (by calling the parent of course).

[Technocrat]

Hmm, I have been trying to figure this out with no luck. Can you give me an example.

[twanvl]

Here is an example:

class A
{
public:
	A();
	A(int);
	A& operator = (int);
	A& operator += (int);
};

class B : public A
{
};

int main()
{
	B b1(1); // error, constructor not inherited
	B b2;
	b2 = 1;  // error, operator = not inherited
	b2 += 1; // ok,    operator += IS inherited
	return 0;
}

The solution to your problem would be to add constructors and assignment operators to your derived class, that just call the parents constructors / assignment operator:

typedef std::basic_string<C, T, A> string_type;
inline TECHSTRING_CL& operator = (const char* str)
{
	string_type::operator = (str);
	return *this;
}