6. Functions

Instructions are grouped into functions. Functions factorize processing and thus combat redundancy. Functions are named and typed. A function specifies the type of arguments it expects and the type of result it returns. A special type exists, called void (no value of this type exists), to signify that a function returns no result (called a procedure in Pascal).

A new special instruction, called return, can be used not only to impose the result of a function, but also to interrupt the invocation of the function and cause it to return the result immediately. The count_lines function, given above as an example, illustrates the use of a return within an endless loop.

The body of a function is a block which, like any other block, can contain variables local to that block. Variables (also known as parameters) of a function have the body of the...