Use & to create a pointer to member : I'm trying to create a function that takes in a string, the reverses it, which is all being done in main. Here's what I have so far. 

    #include <cstring>
    #include <iostream>
    #include <string>
    
    
    std::string str = "zombie";
    
    
    void Reverse( std::string a)
    {
    	
    	char* a1 = a.c_str;
    	char* a2;
    
    	for (int i = (strlen(a1) -1); a1[i]!=0; i--)
    	{
    		a2 += a1[i];
    	}
    
    	str = a2;
    }
    
    int main()
    {
    	Reverse(str);
    
    	std::cout << str << std::endl;
    }

But i keep getting this error. I can't utilize pointers in this question. Any suggestions?
