Lesson 1.3 C++ Functions

• A function in C++ is a block of code that performs a specific task.
• In order to use library functions, we usually need to include the header file in which these library functions are defined.
• Standard Library Functions in C++ are predefined and can be accessed without creating a new function.
• User-defined Functions in C++ are created by users.
• When a function is invoked from any part of the program, it executes the codes defined in the body of the function.
• A parameter is a value that is passed when declaring a function.
• The return statement in C++ can be used to return a value from a function.
• Built-in functions in C++ programming can be accessed by invoking them directly, without needing to write the functions themselves.
• The greet() function can be called by invoking it.
• The function add(int a, int b) in C++ returns the sum of a and b when it is invoked.
• In the function printNum(int num), the int variable num is the function parameter.
• When a function is called, a value is passed to the function parameter.
• Some common library functions in C++ are sqrt(), abs(), isdigit(), etc.
• The syntax to declare a function in C++ is: returnType functionName (parameter1, parameter2,...) { // function body }.
• An example of a function declaration in C++ is: void greet() { cout << "Hello World"; }.
• The name of the function in C++ is greet().
• The return type of the function in C++ is void.
• The empty parentheses in a function declaration in C++ mean it doesn't have any parameters.
• The function body in C++ is written inside {}.
• To call a function in C++, the function declaration is written as: void greet() { cout << "Hello World"; }.