Description: A formal parameter in C++ is a variable declared in a function definition that acts as a placeholder for the values that will be passed to the function when it is invoked. These parameters allow functions to be more flexible and reusable, as they can operate on different data without needing to modify their internal code. Formal parameters are specified in the function’s parameter list and can have various data types, such as integers, floats, strings, among others. When called, the actual values passed to the function are known as arguments. The relationship between formal parameters and arguments is fundamental to the functioning of functions, as formal parameters receive the values of the arguments and use them within the function to perform calculations or manipulate data. This feature is essential in modular programming, where the goal is to divide code into smaller, manageable parts, thus facilitating maintenance and understanding.
History: The concept of formal parameters dates back to the early days of structured programming in the 1970s, when languages like C began to gain popularity. C++ was developed as an extension of C, incorporating object-oriented programming features. Formal parameters became an integral part of function definitions in C++, allowing for greater abstraction and code reuse.
Uses: Formal parameters are used in function definitions to allow these to accept different input values, making them more versatile. They are fundamental in modular programming, where the goal is to divide code into functions that can be reused in different contexts. Additionally, they facilitate the creation of libraries and APIs, where functions can be designed to work with a variety of data types.
Examples: An example of using formal parameters in C++ is the following function that sums two numbers: ‘int sum(int a, int b) { return a + b; }’. Here, ‘a’ and ‘b’ are formal parameters that will receive the values of the arguments when the function is called. When invoking ‘sum(5, 3)’, the values 5 and 3 are assigned to ‘a’ and ‘b’, respectively, and the function will return 8.
