Which are valid declarations? (Choose all that apply)
- int $x
-
int 123
-
int _123
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int #dim
-
int %percent
-
int central_sales_region_Summer_2005_gross_sales
Java identifiers can begin with a letter, underscore, or dollar sign. They cannot begin with a number, hash sign, or percent sign. Thus, $x, _123, and central_sales_region_Summer_2005_gross_sales are valid declarations, while 123, #dim, and %percent are invalid.
To determine the valid declarations, let's go through each option:
Option A) int $x - This option is a valid declaration. In programming languages like C or C++, variable names can start with an underscore (_) or a letter. Therefore, the variable name "$x" is valid.
Option B) int 123 - This option is not a valid declaration. Variable names cannot start with a number.
Option C) int 123 - This option is a valid declaration. Variable names can start with an underscore (), so "_123" is a valid variable name.
Option D) int #dim - This option is not a valid declaration. Variable names cannot start with special characters like "#" in most programming languages.
Option E) int %percent - This option is not a valid declaration. Variable names cannot start with special characters like "%" in most programming languages.
Option F) int central_sales_region_Summer_2005_gross_sales - This option is a valid declaration. Variable names can contain letters, numbers, and underscores. Therefore, "central_sales_region_Summer_2005_gross_sales" is a valid variable name.
The correct options are A, C, and F.