REDUCE
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dynamic-clause |
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[GIVING
operand5]
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| array-clause |
This document covers the following topics:
For an explanation 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 sections Using Dynamic Variables, X-Arrays, Storage Management of X-Group Arrays 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 | N | P | I | F | B | D | T | L | C | G | O | yes | no | ||||
| operand4 | C | S | U | N | P | I | no | no | ||||||||||||
| operand5 | S | I4 | no | yes | ||||||||||||||||
Syntax Element Description:
| dynamic-clause | The REDUCE DYNAMIC VARIABLE statement reduces the
allocated length of a dynamic variable (operand1) to
the length specified (operand2). For more
information, see Dynamic
Clause below.
|
|---|---|
| operand1 | operand1 is the dynamic variable for which the length is to be reduced. |
| operand2 | operand2 is used to specify the length to which the dynamic variable is to be reduced. The value specified must be a non-negative integer constant or a variable of type Integer4 (I4). |
| array-clause | The REDUCE ARRAY statement reduces the number of
occurrences of the X-array (operand3) to the upper
and lower bound specified with (dim[,dim[,dim]]).
For more information, see Array Clause
below.
|
| operand3 | operand3 is the X-array. The
occurrences of the X-array can be reduced. The
index notation
of the array is optional. As index notation only the complete range notation
* is allowed for each dimension.
|
| dim operand4 | 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 (*) must be specified instead of operand4. For more information, see Dimension below. |
| GIVING operand5 |
If the If the |
[SIZE OF]
DYNAMIC [VARIABLE]
operand 1
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
|
|
0
|
|
| (dim[,dim[,dim]]) |
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]]),
.
If REDUCE TO 0 (zero) is specified, all occurrences of the
X-array are released. In other words, the whole array is reduced.
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
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* |
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* |
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:
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* |
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| operand4 | operand4 | |||||||
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.
