Basic C++ problems

I think you're thinking beyond his scope. If he's using strings it's probably for something simple, like storing a word into a variable with cin and printing the same thing out later with cout. I don't think you can do more than that without treating them like arrays of characters, which he obviously isn't doing if he's not doing arrays.

When you declare a variable in C++, you must specify the data type.

Example:
int a = 0.
a is an integer type int and is assigned the value of 0.

Strings are the same way.
You have either
std:tring str = "Hello World";
char[] str = "Hello World";
char* str = "Hello World";
const char* str = "Hello World";