This section describes operators in ConceptDraw Basic and their precedence in complex expressions.
When several operations occur in an expression, each part is evaluated and resolved in a predetermined order. That order is known as operator precedence. Parentheses can be used to override the order of precedence and force some parts of an expression to be evaluated before others. Operations within parentheses are always performed before those outside. Within parentheses, however, normal operator precedence is maintained.
The operators, supported in ConceptDraw Basic, can be divided into 3 groups:arithmetic, comparison, logical. When expressions contain operators from more than one category, arithmetic operators are evaluated first, comparison operators are evaluated next, and logical operators are evaluated last. Within individual categories, operators are evaluated in the order of precedence shown below:
Arithmetic | Comparison | Logical |
Exponentiation (^ or **) | Equality (=) | NOT |
Negation (-) | Inequality (<>) | AND |
Multiplication and division (*, /) | Less than (<) | OR |
Integer division (\) | Greater than (>) | XOR |
Modulo arithmetic (MOD) | Less than or Equal to (<=) | |
Adding and substraction (+, -) | Greater than or Equal to (>=) | IMP |
String concatenation (&) | LIKE | |
Getting address (ADDRESSOF) | IS |
When multiplication and division occur together in an expression, each operation is evaluated as it occurs from left to right. Likewise, when addition and subtraction occur together in an expression, each operation is evaluated in order of appearance from left to right.
The string concatenation operator (&) is not really an arithmetic operator, but in precedence it does fall after all arithmetic operators and before all comparison operators. Similarly, the Like operator, while equal in precedence to all comparison operators, is actually a pattern-matching operator.