A function prototype is a declaration of a function that describes the function’s interface to the compiler. It provides information about the function’s name, return type, and the number and types of arguments that the function takes. The function prototype is usually placed at the beginning of a source file or in a header file, and it allows the compiler to check the function’s usage throughout the program.

Function prototypes are an important part of C++ programming, helping to ensure type safety and code correctness while also making code more readable and maintainable. They provide information, such as the number and type of parameters and the type of return values, to explain the function interface to the compiler. A function prototype may exist either before or after the definition of invoking the function (these prototypes are referred to as global prototypes) .

In C++, a function prototype specifies the name of the function, as well as its return types and parameters. The return types are the data types returned by the function after execution. The function prototype feature in C++ allows us to call the function before it has been declared since the compiler is given information about the function.

Function prototypes are necessary in C++ to call a function in some code before the compiler has seen the function definition. If you forward declare all your functions in the top, you dont have to worry about the order of how you write your function. They also allow you to split your code across multiple files by putting function prototypes in a header file and including that in.