Effect A logical expression formulates a condition for operands. The result of
a logical expression log_exp is a
logical value and can therefore be true or false.
A logical expression is either a single
relational expression
rel_exp or an expression constructed from the
boolean operators
NOT , AND , OR , EQUIV
and one or more logical expressions.
Parentheses are possible here. An atomic part of a composite logical
expression is always one of the following relational expressions:
Comparisons
Comparison expressions
Predicates
Predicate expressions
Predicate functions
Logical expressions can be used as follows:
To formulate conditions in control
statements and other statements used to control the program flow.
in conditional expressions
As an argument of a boolean function
for representing a logical value in a character-like or byte-like data
object.
In WHERE conditions of
processing statements for internal
tables .
Notes
The operand positions operand of most relational expressions are
general expression positions ,
which means that, depending on the expression,
data objects ,
predefined functions ,
functional methods ,
calculation expressions ,
constructor expressions , or
table expressions can be specified.
If, in a logical expression,
functional methods are specified as operands of a relational
expression, they are executed from left to right and from inside to
outside before the relational expression is evaluated. In the case of
joined relational expressions, this is true for
each individual relational expression and not for the overall logical
expression.
Since ABAP does not recognize any Boolean data objects for the logical
values true and false, the result of a logical expression cannot
currently be directly assigned to a data object as is the case for
calculation expressions .
Instead, the return value of a Boolean
function can be used.
Logical expressions cannot be mixed with
calculation expressions .
However, a logical expression can be executed as an argument of a
Boolean function in a suitable
calculation expression.
The program DEMO_EXPRESSIONS also
shows examples of the use of logical expressions, among other things.
Example Logical expression created from a predicate expression, a comparison
expression, and a predicate function using the boolean operator AND
, in a control statement.
IF p1 IS SUPPLIED AND
p1 <(><<)>= upper_limit AND
matches( val = p2 regex = regular_expression ).
...
ENDIF.
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