C Pass By Reference

C does not have the built-in call by reference mechanism as some other languages do, but the same effect can be achieved by passing a pointer-shaped memory address to the function. The function then writes the value through a pointer with an operator*, so that the original variable in the caller goes along with the change. This pattern is often used to return more than one result at a time, for example a function that searches for the maximum value and its index. The advantage is that big data doesn't need to be copied, so it's more economical.