Changes

Once a function is declared it can be called from anywhere in the code, regardless of whether the code is in the same source file as the declaration or in a different file. This is because functions are global by default. After the different source files have been compiled to object code, a tool called the ''linker'' then performs the task of resolving undefined symbols in each object file. When it finds a call to an undefined function in one object file it searches the other object files that comprise the code and any libraries specified until it finds it. If no match is find found the linker will fail with an undefined symbol error.