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C++ Identifiers and Keywords:
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
Keywords
| asm | else |
| Auto | enum |
| Break | extern |
| Case | float |
| Catch | for |
| Char | friend |
| Class | goto |
| Const | if |
| Continue | inline |
| Default | int |
| Delete | long |
| Double | new |
| operator | Template |
| private | This |
| protected | Throw |
| public | try |
| register | typedef |
| return | union |
| short | unsigned |
| signed | virtual |
| sizeof | void |
| static | volatile |
| struct | while |
| switch |