REDUCE
|
[GIVING operand5]
|
This document covers the following topics:
For explanations of the symbols used in the syntax diagram, see Syntax Symbols.
Related statements: EXPAND
| RESIZE
Belongs to Function Group: Memory Management Control for Dynamic Variables or X-Arrays
The REDUCE
statement is used to reduce:
the allocated length of a dynamic variable
(dynamic-clause
), or
the number of occurrences of X-arrays
(array-clause
).
For further information, see also the following sections in the Programming Guide:
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | ||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
S | A | A | U | B | no | no | |||||||||||||
operand2
|
C | S | I | no | no | |||||||||||||||
operand3
|
A | G | A | U | N | P | I | F | B | D | T | L | C | G | O | yes | no | |||
operand4
|
C | S | N | P | I | no | no | |||||||||||||
operand5
|
S | I4 | no | yes |
Syntax Element Description:
Syntax Element | Description |
---|---|
dynamic-clause
|
Dynamic Clause:
The For further information, see Dynamic Clause. |
operand1
|
Dynamic Variable:
|
operand2
|
Target Length of Dynamic
Variable:
The value specified must be a non-negative integer constant or a variable of type Integer 4 (I4). |
array-clause
|
Array Clause:
The For further information, see Array Clause. |
operand3
|
X-Array:
The index notation of the
array is optional. As index notation only the complete range notation
|
dim operand4
|
Dimension:
The lower and upper bound notation
( For further information, see Dimension. |
GIVING
operand5
|
GIVING Clause:
If the If the |
[SIZE OF ]
DYNAMIC [VARIABLE ]
operand1
TO operand2
|
The REDUCE DYNAMIC VARIABLE
statement reduces the
allocated length of a dynamic variable
(operand1
) to the length specified
(operand2
). The allocated memory of the
dynamic variable which is beyond the given length is released immediately,
i.e., when the statement is executed.
If the currently allocated length (*LENGTH
)
of the dynamic variable is greater than the given length,
*LENGTH
is set to the given length and the content of the variable is truncated (but
not modified). If the given length is larger than the currently allocated
length of the dynamic variable, the statement will be ignored.
[OCCURRENCES
OF ] ARRAY
operand3
TO
|
If REDUCE TO 0
(zero) is specified, all occurrences
of the X-array are released. In other words, the whole array is reduced.
The REDUCE ARRAY
statement reduces the number of
occurrences of the X-array
(operand3
) to the upper and lower bound
specified with TO
(dim[,dim[,dim]])
.
An upper or lower bound used in a REDUCE
statement
must be exactly the same as the corresponding upper or lower bound defined for
the array.
DEFINE DATA LOCAL 1 #a(I4/1:*) 1 #g(1:*) 2 #ga(I4/1:*) 1 #i(i4) END-DEFINE ... */ reducing #a (1:10) REDUCE ARRAY #a TO (1:10) /* #a is reduced REDUCE ARRAY #a TO (*:10) /* to 10 occurrences. */ reducing #ga (1:10,1:20) REDUCE ARRAY #g TO (1:10) /* 1st dimension is set to (1:10) REDUCE ARRAY #ga TO (*:*,1:20) /* 1st dimension is dependent and /* therefore kept with (*:*) /* 2nd dimension is set to (1:20) REDUCE ARRAY #a TO (5:10) /* This is rejected because the lower index /* must be 1 or * REDUCE ARRAY #a TO (#i:10) /* This is rejected because the lower index /* must be 1 or * REDUCE ARRAY #ga TO (1:10,1:20) /* (1:10) for the 1st dimension is rejected /* because the dimension is dependent and /* must be specified with (*:*).
For further information, see
Each of the dimensions (dim) specified in the Array Clause is defined using the following syntax:
* |
||||||||
|
: |
|
The lower and upper bound notation
(operand4
or asterisk) to which the
X-array should be reduced is
specified here. If the current value of the upper or lower bound should be
used, an asterisk (*) may be specified in place of
operand4
. In place of *:*
,
you may also specify a single asterisk.
The number of dimensions
(dim
) must exactly match the defined
number of dimensions of the X-array (1, 2 or 3).
When using the REDUCE
statement, it is only possible
to decrease the number of occurrences. If the requested number is larger than
the currently allocated number of occurrences, it will simply be ignored.