Logical Expressions
When writing application programs, you often need to formulate conditions. These are used mostly to
control the flow of the program, or to decide whether to exit a processing block. You formulate a condition using logical expressions. A logical condition can be either true or false.Comparing Data Objects
You can express a logical expression as a comparison between data objects:
.... <f1> <operator> <f2> ...
Depending on the data types of the operands <f1> and <f2>, you can use different logical operators.
Comparisons Between Different Data Types Comparing Strings Comparing Bit Sequences
Other Logical Expressions
Along with data object comparisons, you can formulate logical expressions that check whether data objects meet given conditions:
Checking Whether a Field Belongs to a Range Checking for the Initial Value Checking Selection Criteria Checking Whether a Field Symbol is Assigned
Combining Several Logical Expressions
You can link several logical expressions together in a single condition:
Combining Several Logical Expressions