What are some examples of impure functions in programming?

What are some examples of impure functions in programming?

Impure functions are those that can produce side effects or depend on external states. For example, a function that fetches data from an API or modifies a global variable.

Can you give me a specific code example of an impure function?

Sure! Here's a simple example in JavaScript:

let count = 0;

function increment() {
    count += 1; // This modifies a global variable, making it impure.
    return count;
}

What about pure functions? How do they differ?

Pure functions always produce the same output for the same input and do not cause side effects. For example:

function add(a, b) {
    return a + b; // No side effects, always returns the same result for the same inputs.
}