/sys$common/syshlp/helplib.hlb CC, Language topics, Declarations *Conan The Librarian (sorry for the slow response - running on an old VAX) |
Declarations specify the functions and variables referenced in a program. Declarations in C have the following syntax: declaration: declaration-specifiers [init-declarator-list]; declaration-specifiers: storage-class-specifier [declaration-specifiers] type-specifier [declaration-specifiers] type-qualifier [declaration-specifiers] init-declarator-list: init-declarator init-declarator-list, init-declarator init-declarator: declarator declarator = initializer Note the following items about the general syntax of a declaration: o The storage-class-specifier, type-qualifier, and type-specifier can be listed in any order. All are optional, but, except for function declarations, at least one such specifier or qualifier must be present. Placing the storage-class-specifier anywhere but at the beginning of the declaration is an obsolete style. o Storage-class keywords are auto, static, extern, and register. o Type qualifiers are const, volatile, and __restrict. o The declarator is the name of the object being declared. A declarator can be as simple as a single identifier, or can be a complex construction declaring an array, structure, pointer, union, or function (such as *x, tree(), and treebar[10]). o Initializers are optional and provide the initial value of an object. An initializer can be a single value or a brace-enclosed list of values, depending on the type of object being declared. o A declaration determines the beginning of an identifier's scope. o An identifier's linkage is determined by the declaration's placement and its specified storage class. Consider the following example: volatile static int var_number = 10; This declaration shows a qualified type (a type, int, with a type qualifier, volatile), a storage class (static), a declarator (data), and an initializer (10). This declaration is also a definition, because storage is reserved for the data object var_number. For more information, see HELP CC LANGUAGE_TOPICS DATA_TYPES, HELP CC LANGUAGE_TOPICS STORAGE_CLASSES, and HELP CC LANGUAGE_TOPICS TYPE_QUALIFIERS.
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