Function prototyping is the process of declaring the function’s name, return type, and parameters in the program before the function is defined. It allows the compiler to recognize the function and ensure that it is called correctly throughout the program.

In C++, function prototypes are typically declared at the top of the source code file, before the main() function. The prototype consists of the function’s return type, name, and a list of its parameters, including their data types. Here is an example of a function prototype:

int calcArea(int length, int width);

This prototype declares a function called calcArea() that returns an integer and takes two integer parameters called length and width.

Function prototypes are important because they allow the compiler to check the function calls for proper syntax and ensure that the correct number and type of arguments are being passed. They also allow the compiler to resolve function calls before the function definition is encountered in the code, which can help improve the program’s performance.

It is good practice to include a function prototype for every function in a program, even if the function is defined before it is called. This helps to ensure that the program is easy to read and maintain.