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1、INTERNATIONAL STANDARD ISOIIEC 8631 Second edition 198!3-08-01 Information technology - Program constructs and conventions for their representation Technologies de llinformation - Structures de programmes et normes pour leur rep b) indicates the manner in which constructs can be combined; c) provide
2、s specifications for a set of constructs; d) permits the definition of a variety of subsets of the defined constructs. 4.2 Serial construct This construct contains two or more procedure parts and an implicit control part which determines that the procedure parts are to be executed exactly once in th
3、e sequence given. 4.3 Parallel construct This construct consists of two or more procedure parts and a control part which initiates these procedure parts. Execution of the construct is finished when all initiated procedure parts are completely executed. 4.4 Iterative construct See annex A for symboli
4、c representations. a) Pre-tested iteration 2 Definition of program construct A program construct consists of a set of one or more procedure parts and a control part which may be implicit. Each procedure part consists of one or more operations to be performed or may be null. The control part determin
5、es the manner in which the procedure parts are to be executed. It can consist of a directive and a set of conditions. The control part then activates or de-activates the procedure part(s) depending on the nature of the directive and the values of the conditions. If there is neither directive nor con
6、dition, control is called implicit. 3 How constructs may be combined The only way in which constructs can be combined to build a well-structured program is by replacing a procedure part of one construct by a complete construct. 4 Specification of constructs 4.1 Imperative construct This construct co
7、ntains one procedure part and an implicit control part which determines that the procedure part is executed exactly once. This construct consists of a procedure part and a control part with one condition, the value of which determines whether the procedure part is executed zero or more times. b) Pos
8、t-tested iteration This construct consists of a procedure part and a control part with one condition, the value of which determines whether the procedure part is executed more than once. c) Continuous iteration This construct consists of a procedure part and a control part with an implicit condition
9、 which specifies that the procedure part will be repeated indefinitely. 4.5 Selective choice construct a) Monadic selective This construct consists of a single procedure part and a control part with one condition, the value of which determines whether or not the procedure part is to be executed. b)
10、Dyadic selective This construct consists of two procedure parts and a control part with one condition, the value of which determines which one of the two procedure parts is to be executed. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA
11、 Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 6631 : 1969 (E) c) Multiple exclusive selective This construct consists of a number of procedure parts and a control part with a set of conditions,
12、the values of which determine which one of the procedure parts is to be executed. dj Multiple inclusive selective This construct consists of a number of procedure parts and a control part with a set of conditions, the value(s) of which select zero or more procedure parts to be executed in an undefin
13、ed sequence. 5 Termination In addition to the termination of a construct as defined by its control part, the execution of a construct may be terminated by a TERMINATION operation placed in one or more pro- cedure parts of the construct. The TERMINATION operation shall identify which construct is to
14、be terminated. If the TERMINATION operation is executed, execution of the ident- ified construct and all its inner constructs will immediately cease. A TERMINATION operation that would terminate a parallel construct or a multiple inclusive selective construct is unde- fined. A TERMINATION operation
15、which terminates an outer con- struct does not conform to this International Standard. 6 Definition of subsets The use of a proper subset of the constructs defined in this International Standard and combined in accordance with this International Standard shall be considered to be in confor- mance wi
16、th this International Standard. Use of a construct other than the ones defined in this Inter- national Standard which is functionally equivalent to a legit- imate composition of constructs defined in this International Standard is in conformance with this International Standard. Copyright Internatio
17、nal Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 9631 : 1999 (E) Annex A (informative) Charting notations fo
18、r program constructs The following charting notations for program constructs in columns A to G are examples of applicable graphic representations. The “Reference” column uses the symbols of IS0 5807 and is included for reference only. Symbols from the various columns should not be intermixed. 3 Copy
19、right International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 8631 : 1989 (E) 3 I : L I Copyright Interna
20、tional Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 9631 : 1999 (El 5 Copyright International Organization f
21、or Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 8631 : 1989 (El Copyright International Organization for Standardization Prov
22、ided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC 9631 : 1999 (E) 7 Copyright International Organization for Standardization Provided by IHS under lic
23、ense with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/IEC9631 : 1999 (El UDC 681.3.06 Descriptors : data processing, programming (computers), computer programs. Price based on 7 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 22:13:12 MDTNo reproduction or networking permitted without license from IHS -,-,-