Single-line comments (p. 46) begin with
//. You insert comments to document your programs and improve their readability.
Comments do not cause the computer to perform any action (p. 47) when the program is run— they’re ignored by the compiler.
A preprocessing directive (p. 46) begins with
#and is a message to the C++ preprocessor. Preprocessing directives are processed before the program is compiled.
<iostream>(p. 46) tells the C++ preprocessor to include the contents of the input/output stream header, which contains information necessary to compile programs that output data to the screen or input data from the keyboard.
White space (i.e., blank lines, ...