Identifiers in C language can only be composed of three characters. What are they?

Identifiers in the C language can only be composed of three characters, which are underscores, letters, and numbers. C language identifier naming rules: 1. The identifier must start with the letters a~z, A~Z or an underscore, and can be followed by any number (can be 0) characters; 2. Identifiers are case-sensitive; 3. Identification symbol cannot be a keyword.

Identifiers in the C language can only be composed of three characters, which are underscores, letters, and numbers.

Identifiers in C language should generally follow the following naming rules:

1 Identifiers must start with the letters a~z, A~Z or an underscore, and can be followed by any number of characters (can be 0). These characters can be letters, underscores, and numbers. Other characters are not allowed to appear in identifiers.

2 Identifiers are case-sensitive

3 The length of the identifier, c89 specifies within 31 characters, c99 specifies within 63 characters

4 Key words in C language Words have special meaning and cannot be used as identifiers

5 It is best to use a string with a certain meaning for a custom identifier to facilitate memory and understanding.

Recommended tutorial: "C Language Tutorial"

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