Does C have any tools for doing string addition?

Question

I\'m making a function that returns the derivative of a function that is represented as a tree like

      /   +    \\
     *          ^
   /   \\      /   \\         


        

Answer 1

What you're looking for is string concatenation, and the standard C library function for that is strcat, or better (because arguably safer) strncat.

See http://linux.die.net/man/3/strcat