Firstly the important part:

How do I get say, one character from a string in C++ or perhaps get characters 4-17?

secondly I did try making a string class of my own (called "String") which was meant to be excellent at dealing with this (it wasn't) using a piece of voodoo code that I came up with by accident:

char *string = "q string";
string = "very, very, very, long string";

The main prob is that the program results in a segmentation error
if you try to directly change a single character in string but you can create a temporary traditional array to change it in and then changing string to equaling the array (remember this is all in class so the programmer using String doesn't need to know).
Still I am faced with the question of why it works which would be needed to take out the kinks.

This is why I believe that hiding an implementation can be a hindrance. If this were straight C, it would be easy:

Code:

char blah[] = "My blah string"; // Creates a pointer to a string on the stack
char c = blah[3]; // Stores the 4th character in the string in c

The syntax for doing the same thing in C++ looks like this:

Code:

#include <string>

using namespace std;

int main(void)
{
    string blah("My blah string");
    char c = blah[3];

    printf("c = %c\n", c);

    return(0);
}

You can compile the above program using "g++ -o blah blah.cpp" and it will print out "c = b";

1 Character: As David said, you can get a character by just indexing it like a character array.
Substring: Use the substring function
Luckily C++ already provides this class! Its called string

Please, check out, http://www.cplusplus.com/reference/string/string/

As has been mentioned, you can use std::string::operator[]() or std::string::at() for accessing the character at a certain index. The first is faster, but the second is more “safe” (since it does bounds checking). Also notice that the terminating NUL is not accessible using either of these (so if your string is “std::string s = "hello";” and you want to try “char c = s.at(5);” the result is the throwing of an out-of-range exception and not the ASCII NUL you might expect). Additionally, you can use std::string::substr().
This voodoo code shouldn’t result in segmentation error, but it probably doesn’t do what you thought it would. A very similar statement (if you used an array) would result in a segmentation error. You can’t assign string literals to arrays except at initialization (this is also true of C). You can’t modify string literals assigned to pointers (but you can if they are elements of an array). I.e.,

Well I think that should do the trick. Thanks to all who didn't say that I should use arrays directly.
Oh and 95se, the reason that I wrote my own class for string is because I didn't know about std::string::substr(), hence mine. Thanks anyway.