What you describing is C strings. If your going to be using unknow size strings all over your code in C++ I suggest you use the string class thats in the STL.
Belows an example.
Code:
#include <iostream>
#include <string>
using namespace std;
int main()
{
string str1, str2, str3, str4;
str1 = "The First String";
str2 = "The Second String";
str3 = str1 + " " + str2;
cout << "String 3:" << str3 << endl;;
str4 = str1;
cout << "String 4:" << str1 << endl;
if( str1 == str4 )
cout << "String 1 is equal to string 4" << endl;
else
cout << "String 1 is not equal to string 4" << endl;
str3 = str2;
if( str1 == str3 )
cout << "String 1 is equal to string 3" << endl;
else
cout << "String 1 is not equal to string 3" << endl;
};