Getting a:"member is not of class type" error

I am doing a simple test and when I try to call the member from the class that I created it says that the member isn't of the class type specified. I have called it for the class but I'm still getting the error.

Code:

#ifndef INFIX_CONVERTER_H
#define	INFIX_CONVERTER_H

#include <stack>
#include <map>
#include <string>

/*
Precondition for this converter must be that all input is correct
infix input must consist of digits 0-9 and operators +, -, *, /.
*/
class InfixConverter
{
	std::map<char, int> prec;	//the precendence values of operators
	
	public:
		InfixConverter();
		~InfixConverter() {} 
		std::string toPost(std::string&);
};


#endif

test

Code:

#include <iostream>
#include "Stack.h"
#include "InfixConverter.h"

using std::cout;
using std::cin;
using std::endl;
using std::string;

int main(int argc, char *argv[])
{
	InfixConverter postServe();
	cout << postServe.toPost("2+3+4*5^4") << endl;
	return 0;
}

>std::string toPost(std::string&);

Code:

std::string toPost(const std::string&);

std::string toPost(const std::string&)
If you aren't changing the argument.

If you are, you need to pass it a string object and not a string literal.

still got the error.

Also, I've gotten that same error for different situations, how do I interpret that error in different cases?

>so the compiler assumes that the string being returned is the string being
>passed to it if not explicitly stating one's const to indicate that it's seperate?
That's a fascinating conclusion, but no. You simply can't tell the compiler that the string is writable and then pass a read-only argument.

ahh, I realized that so I changed it, and it's wrong still The code not you

What change have you made?

My first change was the const. My second was changing the parameter from a literal to a string object. Still get the same error.

main.cpp:13: error: request for member `toPost' in `postServe', which is of non-class type `InfixConverter ()()'
Process terminated with status 1 (0 minutes, 0 seconds)

>InfixConverter postServe();
Lose the parens. The compiler thinks you're declaring a function.

Ah! That's different.

check your object declaration. It probably is InfixConverter postServe();.

You will be declaring a function called postServe which takes no arguments and returns an InfixConverter object. That's not what you want.

You don't need (and you shouldn't) use () to create an object with the default constructor

Ahhh, that's the same error I got in another thing I was doing and did the change. I forgot. Thanks.