HP 3000 Manuals HP 3000 Manuals
Concepts of Classes of Data (Cont.) Subscripting Subscripts can be used only when reference is made to an individual element within a list or table of like elements that have not been assigned individual data-names (see the section The OCCURS Clause in the chapter Program Definition). The subscript can be represented either by a numeric literal that is an integer, by a data-name, or by a data-name followed by the operator "+" or "-" , followed by an unsigned integer numeric literal. The data-name must be a numeric elementary item that represents an integer, and the whole subscript must be delimited by the balanced pair of separators, left-parenthesis and right-parenthesis. The subscript data-name can be signed and, if signed, must be positive. The lowest possible subscript value is 1. This value points to the first element of the table. The next sequential elements of the table are pointed to by subscripts whose values are 2, 3,....The highest permissible subscript value, in any particular case, is the maximum number of occurrences of the item as specified in the OCCURS clause. The subscript, or set of subscripts, that identifies the table element is delimited by the balanced pair of separators, left parenthesis and right parenthesis following the table element data-name. The table element data-name appended with a subscript is called a subscripted data-name or an identifier. When more than one subscript is required, they are written in the order of successively less inclusive dimensions of the data organization. Up to 3 subscripts are permitted. For ANS85 only: Up to 7 subscripts are permitted For MF only: Up to 16 subscripts are permitted. General Format.Syntax Rules. 1. The data description entry containing data-name-1 or the data-name associated with condition-name-1 must contain an OCCURS clause or must be subordinate to a data description entry which contains an OCCURS clause. 2. Except as defined in Syntax Rule 7, when a reference is made to a table element, the number of subscripts must equal the number of OCCURS clauses in the description of the table element being referenced. When more than one subscript is required, the subscripts are written in the order of successively less inclusive dimensions of the table. 3. For ANS85 only: The subscript ALLcan be used only when the subscripted identifier is used as a function argument and cannot be used when condition-name-1 is specified. (See the section Arguments in the chapter Program Definition.) 4. Integer-1 can be signed, and if signed, must be positive. 5. Data-name-2 can be qualified and must be a numeric elementary item representing an integer. 6. Index-name-1 must correspond to a data description entry in the hierarchy of the table being referenced which contains an INDEXED BY phrase specifying that index-name. An index described for some other table can be used instead, provided the two tables have elements of the same size. 7. Each table element reference must be subscriptedexcept when such reference appears: a. in a USE FOR DEBUGGING statement b. as the subject of a SEARCH or SORT statement c. in a REDEFINES clause d. in the KEY IS phrase of an OCCURS clause. 8. For OSVS and ANS74 only: The mixing of subscripts and indices in the same identifier is illegal. General Rules. For MF only: If NOBOUND system directive is specified, these General Rules are not applicable at run time. For a description of the BOUND directive, see your COBOL System Reference. 1. The value of the subscript must be a positive integer. The lowest possible occurrence number represented by a subscript is 1. The first element of any given dimension of a table is referenced by an occcurrence number of 1. Each successive element within that dimension of the table is referenced by occurrence numbers of 2, 3,....The highest permissible occurrence number for any given dimension of the table is the maximum number of occurrences of the item specified in the associated OCCURS clause. 2. The value of the index referenced by index-name-1 corresponds to the occurrence number of an element in the associated table. 3. The value of the index referenced by index-name-1 must be initialized before it is used as a subscript. An index can be given an initial value by either a PERFORM statement with the VARYING phrase, a SEARCH statement with the ALL phrase, or a SET statement. An index can be modified only by the PERFORM, SEARCH, and SET statements. 4. If integer-2 (ANS85) or integer-3 is specified, the value of the subscript is determined by incrementing by the value of integer-2(ANS85) or integer-3 (when the operator "+" is used) or by decrementing by the value of integer-2 (ANS85) or integer-3 (when the operator "-" is used), either (ANS85) the occurrence number represented by the value of the index referenced by index-name-1 or the value of the data item referenced by data-name-2 (ANS85). Indexing References can be made to individual elements within a table of like elements by specifying indexing for that reference. An index is assigned to that level of the table by using the INDEXED BY phrase in the definition of a table. A name given in the INDEXED BY phrase is known as an index-name and is used to refer to the assigned index. The value of an index corresponds to the occurrence number of an element in the associated table or any other table. An index-name must be initialized before it is used as a table reference. An index-name can be given an initial value by a SET statement. Unlike a subscript, which is simply a numeric data item or literal, an index is a special type of item and holds a representation of an occurrence number. The form of this representation can vary; the contents of an index cannot be regarded as a numeric value. Direct indexing is specified by using an index-name in the form of a subscript. Relative indexing is specified when the index-name is followed by the operator "+" or "-", followed by an unsigned integer numeric literal, all delimited by the balanced pair of separators left parenthesis and right parenthesis following the table element data-name. The occurrence number resulting from relative indexing is determined by incrementing (where the operator "+" is used) or decrementing (where the operator "-" is used), by the value of the literal, the occurrence number represented by the value of the index. When more than one index-name is required, they are written in the order of successively less inclusive dimensions of the data organization. A table can be indexed only by the index described in its INDEXED BY phrase. For OSVS and VSC2 only: An index described for some other table can be used instead provided the two tables have elements of the same size. At the time of execution of a statement which refers to an indexed table element, the value contained in the index used to index it must neither correspond to a value less than one nor to a value greater than the highest permissible occurrence number of an element of the associated table. This restriction also applies to the value resulting from relative indexing. For MF only: If NOBOUND is specified, this rule is not applicable at run time. For a description of the BOUND directive, see your COBOL System Reference. Up to 3 index-names can be used with a data-name. For ANS85 only: Up to 7 index-names can be used with a data-name. For MF only: Up to 16 index-names can be used with a data-name. The general format for indexing is included in the general format for subscripting earlier in this chapter. For ANS85 only: Function-identifier A function-identifieris a syntactically correct combination of character strings and separators that uniquely references the data item resulting from the evaluation of a function. General Format. FUNCTION function-name-1 [({argument-1}...)] [reference-modifier] Syntax Rules. 1. Argument-1 must be an identifier, a literal, or an arithmetic expression. Specific rules governing the number, class, and category of argument-1 are given in the definition of each function. (See the section Intrinsic Functions in the chapter Program Definition.) 2. A reference modifier can be specified only for functions of the category alphanumeric. 3. A function-identifier that references an alphanumeric function can be specified anywhere in the general formats that an identifier is permitted and where the rules associated with the general formats do not specifically prohibit reference to functions, except: a. as a receiving operand of any statement b. where the rules associated with the general formats require the data item being referenced to have particular characteristics (such as class and category, usage, size, sign, and permissable values) and the evaluation of the function according to its definition and the particular arguments specified would not have these characteristics. 4. A function-identifier that references an integer or numeric functioncan be used only in an arithmetic expression , or as the source of a MOVE statement (MF) . General Rules. 1. The class and other characteristics of the function being referenced are determined by the function definition. 2. At the time reference is made to a function, its arguments are evaluated individually in the order specified in the list of arguments, from left to right. An argument being evaluated can itself be a function-identifier or can be an expression containing function-identifiers. There is no restriction preventing the function referenced in evaluating an argument from being the same function as that for which the argument is specified. In other words, recursion is permitted. For MF only: If a function is expecting an interger argument, then if a floating-point arguement is provided, the value will be rounded to the nearest integer, otherwise andy franctional part will be truncated. For ANS85 only: Reference Modification Reference modificationdefines a data item by specifying a leftmost character and length for the data item. Unless otherwise specified, it is allowed anywhere an identifierreferencing an alphanumeric data item is permitted. General Format.
NOTE Data-name-1 and FUNCTION function-name-1 (argument-1) are shown in the above format to provide context and are not part of the reference-modifier.
Syntax Rules. 1. Data-name-1 must reference a data item whose usage is DISPLAY. 2. Leftmost-character-position and length must be arithmetic expressions. 3. Unless otherwise specified, reference modification is allowed anywhere an identifier referencing a data item of the class alphanumeric is permitted. 4. Data-name-1 can be qualified and/or subscripted. 5. The function referenced by function-name-1 and its arguments, if any, must be an alphanumeric function. General Rules. 1. Each character of a data item referenced by data-name-1 or by function-name-1 and its arguments, if any, is assigned an ordinal number incrementing by one from the leftmost position to the rightmost position. The leftmost position is assigned the ordinal number one. If the data description entry for data-name contains a SIGN IS SEPARATE clause, the sign position is assigned an ordinal number within that data item. 2. If the data item referenced by data-name-1 is described as numeric, external floating-point (MF, VSC2 and OSVS only) numeric edited, alphabetic, or alphanumeric edited, it is operated upon for purposes of reference modificationas if it were redefined as an alphanumeric data item of the same size as the data item referenced by data-name. 3. Reference modification for an operand is evaluated as follows: a. If subscripting is specified for the operand, the reference modification is evaluated immediately after evaluation of the subscripts. If an ALL subscriptis specified for an operand, the reference-modifieris applied to each of the implicitly specified elements of the table. b. If subscripting is not specified for the operand, the reference modification is evaluated at the time subscripting would have been evaluated if subscripts had been specified. c. If reference modification is specified in a function reference, the reference modification is evaluated immediately after evaluation of the function. 4. Reference modification creates a unique data item that is a subset of the data item referenced by data-name-1 or by function-name-1 and its arguments, if any. This unique data item is defined as follows: a. The evaluation of leftmost-character-position specifies the ordinal position of the leftmost character of the unique data item in relation to the leftmost character of the data item referenced by data-name-1 or function-name-1 and its arguments, if any. Evaluation of leftmost-character-position must result in a positive nonzero integer less than or equal to the number of characters in the data item referenced by data-name-1 or by function-name-1 and its arguments, if any: For MF and VSC2 only: The results are rounded if the expression is in floating-point, and truncated if the expression is in fixed-point. For MF only: Evaluation of leftmost-character-position may result in a positive non-integer value, greater than one, in which case the value is truncated to be integer-part. b. The evaluation of length specifies the size in bytes of the data item to be used in the operation. The evaluation of length must result in a positive nonzero integer. The sum of leftmost-character-position and length minus the value one, must be less than, or equal to, the number of characters in the data item referenced by data-name-1 or by function-name-1 and its arguments, if any. If length is not specified, the unique data item extends from and includes the character identified by leftmost-character-position, up to and including the rightmost character of the data item referenced by data-name-1 or by function-name-1 and its arguments, if any. For MF and VSC2 only: The results are rounded if the expression is in floating-point, and truncated if the expression is in fixed-point. 5. The unique data item is considered an elementary data item without the JUSTIFIED clause. When a function is referenced, the unique data item has the class and category of alphanumeric. When data-name-1 is specified, the unique data item has the same class and category as that defined for the data item referenced by data-name except that the categories numeric, numeric edited, alphanumeric edited and external floating-point (MF, VSC2 and OSVS) are considered class and category alphanumeric. 6. For OSVS only: If the OSVS system directiveis set, reference modificationcannot be used in conditional expressions (see the chapter Program Definition for a description of conditional expressions). Identifier An identifier is a syntactically correct sequence of character-strings and separators used to reference data uniquely. When a data item other than a function is being referenced, identifier is a term used to reflect that a data-name, if not unique in a program, must be followed by a syntactically correct combination of qualifiers, subscripts, or reference-modifiersnecessary for uniqueness of reference. General Formats. Format 1 (ANS85 only).Format 2.Where subscript represents either subscripting (see the section Subscripting earlier in this section) or indexing (see the section Indexing earlier in this section). Rules on subscripting and indexing are: 1. The words IN and OF are equivalent. 2. A data-name must neither be subscripted nor indexed when it is being used as an index, or subscript. 3. Indexing is not permitted where subscripting is not permitted. 4. An index can be modified only by the SET, SEARCH, and PERFORM statements. Data items described by the USAGE IS INDEX clause permit storage of the values associated with index-names as data. The form in which these values are stored is system-dependent. See your COBOL System Reference for details. Such data items are called index data items. 5. Literals used as subscripts must be positive numeric integers. Literals used for relative subscripting and indexing must be unsigned numeric integers.
![[]](../../pic3k/M015064/FFN153c50.gif)
![[]](../../pic3k/M015064/FFN163c50.gif)
![[]](../../pic3k/M015064/FFN173c50.gif)
![[]](../../pic3k/M015064/FFN183c50.gif)