Functional Programming

Read this introduction to functional programming, through Section 3.3.1. As you will see from the article's index, many languages support functional programming, including (although not mentioned in the article) C/C++.

4. Comparison to imperative programming

Side-by-side comparison of Imperative vs. Functional programming

The following two examples (written in JavaScript) achieve the same effect - they multiply all even numbers in an array by 10 and add them all, storing the final sum in the variable "result".

Traditional Imperative Loop:

const numList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
let result = 0;
for (let i = 0; i < numList.length; i++) {
  if (numList[i] % 2 === 0) {
    result += (numList[i] * 10)
  }
}

Functional Programming with higher-order functions:

const result = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
               .filter(n => n % 2 === 0)
               .map(a => a * 10)
               .reduce((a, b) => a + b)