ok im working on upgrading a simple encryption program that i had running then lost due to HDD failure. ok but im comming up with a few questions about C++..... well more like how-do-i's really:

how do i make the program clear the screen fully on its own like i would if i gave the command 'clear' at the prompt?

how do i get a key from a file then pass it along into a string for use in the encryption, just a char string nothing fancy.

and im also not fully understanding passing things to functions...... i can use functions and normaly if i need something passed back and forth ill just use global varriables (i know this isnt the best way, thats why im asking) ok you have the protoytpe at top: "int area(int length, int width);" then below the main() you have it again but it can be different?!?: "int area(int yardLength, int yardWidth){"????? im missing something here arent i? thats what it says in my (i know, i know) TY21 book as an example........ how can they be different if its the same thing that your defining insted of declaring......???? im really missing something arent i?

and i just wanna make sure that i have one little thing strait in my mind also before i go on. when you call a function in the code, then it return a value, the main() (or what ever function called it) treats it like its just what got returned...... right? did i explain that right? i hope so.

well i suck at coding just yet so ill probly have more questions soon. thanks