In C++, some of the following are legal identifiers. Which? (Choose 2 right answers) Select one or more: a. Xyz b. xy_z c. 9xyz d. xyz! e. X+yz
The Correct Answer and Explanation is:
Correct answers:
- a. Xyz
- b. xy_z
Explanation:
In C++, identifiers are the names used to identify variables, functions, arrays, classes, and other user-defined elements. There are specific rules for forming valid identifiers:
- An identifier must begin with a letter (A–Z or a–z) or an underscore (_) character.
- Subsequent characters can include letters, digits (0–9), or underscores.
- Identifiers cannot begin with a digit.
- Identifiers cannot contain symbols such as
!,+,@,#, etc. - Keywords reserved by the language cannot be used as identifiers.
Let us evaluate each option based on these rules:
- a. Xyz
This is a valid identifier. It starts with a letter and contains only letters. No special characters or digits are used inappropriately. - b. xy_z
This is also valid. It begins with a letter and includes an underscore, which is allowed. - c. 9xyz
Invalid. Identifiers cannot begin with a digit. This breaks the first rule. - d. xyz!
Invalid. The exclamation mark!is not allowed in identifiers. - e. X+yz
Invalid. The plus sign+is not permitted within an identifier. It is considered an operator, not a legal character for names.
Therefore, only a. Xyz and b. xy_z meet the requirements for legal identifiers in C++. These follow the language’s syntax rules for naming variables or other elements, making them safe and acceptable for use in a C++ program
