Returning Values

A function can return a value using the return keyword. To avoid unexpected errors, the value returned by a function should be compatible with the return type of the function. For instance, the return 0; statement we have seen at the end of the main functions returns an integer which is compatible with the return type int listed right before the function name main.

Note: By convention, the main function is made to return 0 to indicate that the program has run to completion with success.

Functions whose return type is void don’t return anything.

Example: A function that computes

Let’s consider another example of a function, one where we want our function to do some computations and return the computed value. Let’s write a function to compute Fibonacci numbers. Fibonacci numbers are defined as:

$$\begin{array}{rl}{\displaystyle F_0}& {\displaystyle =0}\\ {\displaystyle F_1}& {\displaystyle =1}\\ {\displaystyle F_n}& {\displaystyle =F_{n-1}+F_{n-2}\text{where }n\ge 2}\end{array}$$ ...