Rational Developer for System z
Enterprise PL/I for z/OS, Version 3.8, Language Reference Manual

Data declarations

Explicit declaration
DECLARE statement
Factoring attributes
Implicit declaration
Scope of declarations
INTERNAL and EXTERNAL attributes
RESERVED attribute
SUPPRESS attribute
Data alignment
ALIGNED and UNALIGNED attributes
Defaults for attributes
Language-specified defaults
DEFAULT statement
Restoring language-specified defaults
Arrays
DIMENSION attribute
DIMACROSS attribute
Examples of arrays
Subscripts
Cross sections of arrays
Structures
Unions
UNION attribute
Structure/union qualification
LIKE attribute
Examples
NOINIT attribute
Aggregate combinations and mapping
Combinations of arrays, structures, and unions
Cross sections of arrays of structures or unions
Structure and union operations
Structure and union mapping

When a PL/I program is executed, it can manipulate many different data items of particular data types. Each data item, except an unnamed arithmetic or string constant, is referred to in the program by a name. Each data name is given attributes and a meaning by a declaration (explicit or implicit).

Most attributes of data items are known at the time the program is compiled. For nonstatic items, attribute values (the bounds of the dimensions of arrays, the lengths of strings, area sizes, initial values) and some file attributes can be determined during execution of the program. Refer to Block activation for more information.

Data items, types, and attributes are introduced in Data elements.

This chapter discusses explicit and implicit declarations, scalar, array, structure, and union declarations, scope of names, data alignment, and default attributes.


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