An example of a function in a program is a sum function. Here’s a simple implementation: define a function named sum that takes two arguments. Call it using variables a and b: int a = 5; int b ...

Another tenet of functional programming philosophy is not to modify data outside the function. In practice, this means to avoid modifying the input arguments to a function.

Functions manipulate data and return a value to the main program. Note: AQA pseudo-code does not use a different keyword to show the difference between a procedure and a function.

Further programming language operations - AQA Types of subroutines - procedures and functions. Proficient programming requires knowledge of many techniques.