Select the correct answerWhich of the following is not a valid variable name in C?Options123variablemyVariable_variablevariable123

Correct Answer

The correct answer is 123variable.

Explanation

In C programming, variable names (also known as identifiers) must adhere to specific rules. Here are the fundamental rules for naming variables:

1. A variable name must begin with a letter (a-z, A-Z) or an underscore (_).
2. Subsequent characters in the variable name can include letters, digits (0-9), and underscores.
3. Variable names are case-sensitive, meaning myVariable and myvariable would be considered different identifiers.
4. Variable names cannot be a reserved keyword in C.

Given the options:

• 123variable starts with digits, which is not allowed.
• myVariable, _variable, and variable123 adhere to the naming rules.

Therefore, 123variable is not a valid variable name in C.