What are Free Functions in C ?

Understanding Free Functions in C

Within the context of C programming, the concept of "free functions" often arises. While reading documentation related to boost::test, the term "free function" may encounter, which warrants further clarification.

A free function in C is defined as a function that exists independently of any class or struct. In other words, free functions are not associated with a particular object but rather operate globally within the program.

Contrary to initial assumptions, free functions can return values and receive parameters like other functions. The defining characteristic of a free function is its lack of association with an object.

Consider the following code example:

// A free function
int add(int a, int b) {
  return a + b;
}

// A member function of struct X
struct X {
  void increment() {
    value++;
  }
  private:
    int value = 0;
};

In this example, the add function is a free function because it operates independently of any object. On the other hand, the increment function is a member function of the X struct and can only be invoked on an instance of X.

It's important to remember that free functions can be declared anywhere within a program's scope, allowing for a more flexible and modular approach to code organization.

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