In C program, variable can not start with:

Question

Accepted Answer

The correct option is (4):
A number and A special symbol other than underscore

The correct option is (4):
The foundation of the C programming language is built upon strict rules for naming identifiers, which include variable names. A C variable name must begin with either an alphabet (A-Z, a-z) or the underscore character (\_). It is a fundamental syntax rule that a variable cannot start with a digit (0-9). For instance, `1data` is an illegal variable name, although `data1` is perfectly valid. Moreover, the C standard restricts the use of special symbols in identifiers to only the underscore. Therefore, starting a variable name with a special character like `@`, `#`, or `$` is also prohibited. Since the variable cannot start with a number *and* it cannot start with any special symbol other than the underscore, Option 4 provides the most comprehensive and accurate description of the forbidden starting characters.

The incorrect option is (1):
An alphabet
This option is incorrect because starting a variable name with an alphabet is the primary and most standard convention in C programming. Both lowercase (e.g., `sum`, `index`) and uppercase (e.g., `TOTAL`, `Limit`) letters are absolutely permitted as the first character of a variable name. The rule is designed to distinguish identifiers from numeric constants.

The incorrect option is (2):
A number
While it is true that a variable cannot start with a number, this option is only partially correct and incomplete. A number is indeed one type of character with which an identifier cannot begin. However, C programming rules also forbid starting a variable name with most special symbols. Since a more complete and accurate option (Option 4) that combines all forbidden starting characters is available, this single option is not the best answer.

The incorrect option is (3):
A special symbol other than underscore
This option is also partially correct but incomplete. It accurately identifies that special symbols like `$` or `%` cannot start a variable name, and correctly excludes the underscore (\_), which *is* permitted (e.g., `\_count`). Nevertheless, the rule also strictly prohibits a variable from starting with a number. Because this option only accounts for the special symbols and ignores the numbers, it is not the most comprehensive answer.