ISO/IEC 9899:2018 情報技術—プログラミング言語— C | ページ 6

3.1

access (verb)

(execution-time action) to read or modify the value of an object

Note 1 to entry: Where only one of these two actions is meant,"read" or"modify" is used.

Note 2 to entry:"Modify" includes the case where the new value being stored is the same as the previous value.

Note 3 to entry: Expressions that are not evaluated do not access objects.

3.2

alignment

requirement that objects of a particular type be located on storage boundaries with addresses that are particular multiples of a byte address

3.3

argument

actual argument

DEPRECATED: actual parameter

expression in the comma-separated list bounded by the parentheses in a function call expression, or a sequence of preprocessing tokens in the comma-separated list bounded by the parentheses in a function-like macro invocation

3.4

behavior

external appearance or action

3.5

bit

unit of data storage in the execution environment large enough to hold an object that can have one of two values

Note 1 to entry: It need not be possible to express the address of each individual bit of an object.

3.6

byte

addressable unit of data storage large enough to hold any member of the basic character set of the execution environment

Note 1 to entry: It is possible to express the address of each individual byte of an object uniquely.

Note 2 to entry: A byte is composed of a contiguous sequence of bits, the number of which is implementation-defined. The least significant bit is called the low-order bit; the most significant bit is called the high-order bit.

3.7

character

3.8

constraint

restriction, either syntactic or semantic, by which the exposition of language elements is to be interpreted

3.9

correctly rounded result

representation in the result format that is nearest in value, subject to the current rounding mode, to what the result would be given unlimited range and precision

Note 1 to entry: In this document, when the words"correctly rounded" are not immediately followed by"result", this is the intended usage.

3.10

diagnostic message

message belonging to an implementation-defined subset of the implementation’s message output

3.11

forward reference

reference to a later subclause of this document that contains additional information relevant to this subclause

3.12

implementation

particular set of software, running in a particular translation environment under particular control options, that performs translation of programs for, and supports execution of functions in, a particular execution environment

3.13

implementation limit

restriction imposed upon programs by the implementation

3.14

memory location

either an object of scalar type, or a maximal sequence of adjacent bit-fields all having nonzero width

Note 1 to entry: Two threads of execution can update and access separate memory locations without interfering with each other.

Note 2 to entry: A bit-field and an adjacent non-bit-field member are in separate memory locations. The same applies to two bit-fields, if one is declared inside a nested structure declaration and the other is not, or if the two are separated by a zero-length bit-field declaration, or if they are separated by a non-bit-field member declaration. It is not safe to concurrently update two non-atomic bit-fields in the same structure if all members declared between them are also (nonzero-length) bit-fields, no matter what the sizes of those intervening bit-fields happen to be.

 struct {
 char  a;
 int  b:5, c:11,:0, d:8;
 struct {  int  ee:8;} e;
}

3.15

object

region of data storage in the execution environment, the contents of which can represent values

Note 1 to entry: When referenced, an object can be interpreted as having a particular type; see 6.3.2.1.

3.16

parameter

formal parameter

DEPRECATED: formal argument

object declared as part of a function declaration or definition that acquires a value on entry to the function, or an identifier from the comma-separated list bounded by the parentheses immediately following the macro name in a function-like macro definition

3.17

recommended practice

specification that is strongly recommended as being in keeping with the intent of the standard, but that might be impractical for some implementations

3.18

runtime-constraint

requirement on a program when calling a library function

Note 1 to entry: Despite the similar terms, a runtime-constraint is not a kind of constraint as defined by 3.8, and need not be diagnosed at translation time.

Note 2 to entry: Implementations that support the extensions in Annex K are required to verify that the runtime-constraints for a library function are not violated by the program; see K.3.1.4.

Note 3 to entry: Implementations that support Annex L are permitted to invoke a runtime-constraint handler when they perform a trap.

3.19

value

precise meaning of the contents of an object when interpreted as having a specific type

3.20

⌈x⌉

ceiling of x

the least integer greater than or equal to x

3.21

⌊x⌋

floor of x

the greatest integer less than or equal to x