What are C++ Identifiers?
In a program to identify a function, variable, class or any of the other user defined item you use identifiers so, this concept is known as Identifiers. The identifier can be started with a letter ‘A’ to ‘Z’ or ‘a’ to ‘z’ or from underscore (_) which is followed by zero or more letters, underscores and digits (0 to 9). The C++ does not allow punctuation characters such as $, % and @ within identifiers. Some of the valid identifiers are: shyam, _max, j_47, name10.
And invalid identifiers are :
4xyz, x-ray, abc 2.
Rules for naming Identifier
- Identifiers are case sensitive because C++ is case sensitive i.e. uppercase letters and lowercase letters are different.
- You cannot start name of an identifier with a digit whereas underscore can be used as first character while naming identifier.
- Other special characters are not allowed while naming an identifier.
- You cannot use keywords as identifier.
What are Keywords?
Keywords are the reserved identifiers that cannot be used as names for the variables in a program. The keywords cannot be used for:
- Declaring the class name
- Declaring the object name
- Declaring the variable name
- Declaring the function name