Question

Identify the following variables as valid or invalid: a. If b. True c. NUM21 d. 21_NUM​

Answer 1

Explanation:

(a) Invalid

Because if is a keyword in java and keywords cannot be used as variable names

(b) Valid

(c) Valid

(d) Invalid

Because variable name cannot start with any digit.

Note:-

RULES OF WRITING VARIABLES IN JAVA:-

1) Variables never start with any digit.(14ST - wrong)

2) White space is not allowed( Number 1 - wrong Number1- correct

3) Special characters are not allowed.

=> Only 2 special characters you can use,i.e.

• Dollar($)
• Underscore(_) -----> total_mark- correct

abc$- correct

abc#- wrong

=> User can declare the special character at any position( beginning, mid, end) ------> _x - correct

a$bc- correct

4) Java keywords cannot be used as variable names.

• Few examples of keywords:-

1. byte
2. short
3. int
4. long
5. float
6. double
8. string
9. boolean
10. final
11. finally
12. public
13. class
14. private
15. void
16. protected
17. for
18. if
19. else, etc.

5) Variable can contain uppercase character or lower case character or both. ------> SUM - correct

sum - correct

Sum - correct

Hope it helps....

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