How do I set an environment variable in C++?
NAME putenv - change or add an environment variable SYNOPSIS #include <stdlib.h> int putenv(char *string); DESCRIPTION The putenv() function adds or changes the value of environment variables. The argument string is of the form name=value. If name does not already exist in the environment, then string is added to the environment. If name does exist, then the value of name in the environment is changed to value. The string pointed to by string becomes part of the environment, so altering the string changes the environment.
On Win32 it's called _putenv I believe.
See SetEnvironmentVariable also if you're a fan of long and ugly function names.
I'm not positive environment variables are what you need, since they aren't going to be used outside of this run of the program. No need to engage the OS.
You might be better off having a singleton class or a namespace that holds all these values, and initialize them when you start the program.