Identifiers used In C A c program consists of two types of elements, user defined and pre-defined.identifier is nothing but a name given to those elements. An identifier is a word used by programmer to name a variable,function or label.identifiers consists of letters and digits,in any order , except that the first character must be a letter.Both upper and lowercase letters can be used. Identifiers are :- 1. Keywords. 2. Variables. 3. Constants. 4. Numbers. 5. Data types keywords :- Keywords are nothing but system defined identifiers. Keywords are reserved words of the language.they have specific meaning in the language and cannot be used by the programmer as variable or constant names. c language specifies 32 keywords and other reserved keywords. Keywords are listed below : auto If r...