In C program, what is the right syntax to access value of structure variable book {price, page}?

Question

Accepted Answer

The correct option is (1):
printf(""%d%d"", book.price, book.page);

The fundamental principle for accessing members of a structure in C programming is the use of the **dot operator (.)**. When you declare a structure variable, such as `book` in this scenario, the dot operator acts as the member selection operator, allowing you to directly reach the individual elements (fields) stored within that variable. The required syntax is always the **structure variable name**, followed by the **dot operator**, and then the **member name** you wish to access: `structure_variable.member_name`. Therefore, to access the values of the `price` and `page` fields contained within the `book` variable, the correct expressions are `book.price` and `book.page`, making Option 1 the only syntactically correct way to print these values.

The incorrect option is (2):
printf(""%d%d"", price.book, page.book);

This option presents an inverse syntax for accessing structure members, which is invalid in the C language. The dot operator always operates on the structure variable itself, not the member name. Here, it mistakenly tries to use `price` as the structure variable and `book` as the member, and similarly with `page.book`. In reality, `price` and `page` are the members of the structure variable `book`, and reversing this hierarchy is a compiler error. This syntax fails to correctly identify the composite variable (`book`) that contains the fields being accessed.

The incorrect option is (3):
printf(""%d%d"", price::book, page ::book);

The double colon operator (`::`) is known as the scope resolution operator, and it is a feature of C++, not C. In C++, this operator is primarily used to access static class members or to specify which namespace a variable belongs to. Since the question specifically asks for the syntax within a **C program**, the inclusion of the scope resolution operator makes this syntax incorrect and non-functional within a C compiler. This operator has no defined purpose for accessing members of a standard C structure variable.

The incorrect option is (4):
printf(""%d%d"", price-\>book, page-\>book);

This option uses the arrow operator (`->`), which is another valid method for accessing structure members, but only when operating on a **pointer** to a structure. The arrow operator is a shorthand for dereferencing a structure pointer and then using the dot operator (e.g., `(*structure_pointer).member_name`). Because the variable `book` is specified in the problem as a structure *variable* and not a pointer to a structure, the `->` operator is inappropriate and will result in a compilation error. Furthermore, the format incorrectly attempts to use the member names (`price` and `page`) as the structure pointers, compounding the error.