Basic C++ problems

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";

I do string str = "Hello World"