Q.Write the rules for forming identifier name.

An identifier is the name given to a program element (variable, function, array, etc.), and C fixes definite rules for framing valid identifier names. …

[!TLDR]

An identifier must start with a letter or underscore, contain only letters/digits/underscore, avoid keywords and spaces, and is case-sensitive.

An identifier is the name used to identify a variable, function, array, or other user-defined item. C lays down the following rules for forming a valid identifier name:

1. The first character must be an alphabet (A-Z or a-z) or an underscore ( _ ).
2. The subsequent characters may be letters, digits (0-9) or the underscore.
3. No special characters (except the underscore) and no blank spaces are allowed.
4. A keyword (reserved word such as int, for, while) cannot be used as an identifier.
5. Identifiers are case-sensitive - Sum, SUM and sum are three different names.
6. It should preferably be short and meaningful; many compilers treat only the first few characters as significant. …