The rest of this chapter describes the form and meaning of declarations for variable types summarized in this list. In particular, the remaining sections explain how to declare the following:
| Type of Variable | Description |
| Simple variables | Single-value variables with integral or floating-point type |
| Arrays | Variables composed of a collection of elements with the same type |
| Pointers | Variables that point to other variables and contain variable locations (in the form of addresses) instead of values |
| Enumeration variables | Simple variables with integral type that hold one value from a set of named integer constants |
| Structures | Variables composed of a collection of values that can have different types |
| Unions | Variables composed of several values of different types that occupy the same storage space |
A declarator is the part of a declaration that specifies the name that is to be introduced into the program. It can include modifiers such as * (pointer-to) and any of the Microsoft calling-convention keywords.
Microsoft Specific —>
In the declarator
__declspec(thread) char *var;
char is the type specifier, __declspec(thread) and * are the modifiers, and var is the identifier’s name.
END Microsoft Specific
You use declarators to declare arrays of values, pointers to values, and functions returning values of a specified type. Declarators appear in the array and pointer declarations described later in this chapter.
Syntax
declarator :
pointer opt direct-declarator
direct-declarator :
identifier
( declarator )
direct-declarator [ constant-expression opt ]
direct-declarator ( parameter-type-list )
direct-declarator ( identifier-list opt )
pointer :
* type-qualifier-list opt
* type-qualifier-list opt pointer
type-qualifier-list :
type-qualifier
type-qualifier-list type-qualifier
Note See the syntax for declaration in Overview of Declarations, or see Appendix A, C Language Syntax Summary, for the syntax that references a declarator.
When a declarator consists of an unmodified identifier, the item being declared has a base type. If an asterisk (*) appears to the left of an identifier, the type is modified to a pointer type. If the identifier is followed by brackets ([ ]), the type is modified to an array type. If the identifier is followed by parentheses, the type is modified to a function type. For more information about interpreting precedence within declarations, see Interpreting More Complex Declarators.
Each declarator declares at least one identifier. A declarator must include a type specifier to be a complete declaration. The type specifier gives the type of the elements of an array type, the type of object addressed by a pointer type, or the return type of a function.
Array and pointer declarations are discussed in more detail later in this chapter. The following examples illustrate a few simple forms of declarators:
int list[20]; /* Declares an array of 20 int values named list */
char *cp; /* Declares a pointer to a char value */
double func( void ); /* Declares a function named func, with no
arguments, that returns a double value */
int *aptr[10] /* Declares an array of 10 pointers */
Microsoft Specific —>
The Microsoft C compiler does not limit the number of declarators that can modify an arithmetic, structure, or union type. The number is limited only by available memory.
END Microsoft Specific