Every C++ program has at least one function (main), and all but the most trivial programs define additional functions. The C++ standard library provides numerous functions that your program can call. This chapter discusses how to declare, define, and call functions. A function declaration tells the compiler about a function's name, return type, and parameters. A function definition also provides the body of the function.
See Chapter 3 for more information about function call expressions and Chapter 4 for information about statements, which make up function bodies. This chapter presents information that is common to all kinds of functions. For characteristics that are unique to member functions, see Chapter 6, and for information that pertains specifically to function templates, see Chapter 7.
The syntax descriptions in this chapter are informal. See Chapter 12 for a precise BNF grammar.