The software maintains a series of system variables that represent either fixed values ($ZimOS) or values that fluctuate dynamically with the current status of the software ($InTransaction) or of application objects (ThisWindow.WindowTag). System variables resemble global variables in nature. The software automatically sets or resets the values of system variables to reflect the status of…
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Although every application has its own unique requirements, the individual components of applications are often very similar. For example, menus, pop-up windows, and data entry forms and displays are common components of most applications. Pop-up windows, for instance, can vary in size, location and contents, but the commands to present them to the application user…
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Operator Rule of Precedence Conditional Operators are evaluated first NOT NOT is evaluated first. AND AND is evaluated next. OR, XOR OR and XOR are evaluated last. Note: Operators of equal precedence are evaluated from left to right in the expression.Parentheses can be used to explicitly determine the order of evaluation, overriding the order described…
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Boolean expressions use Boolean operators to compare operands (typically, conditional expressions). When evaluated, Boolean expressions yield a logical result (true or false), depending on the nature of the Boolean operator and the values of the conditional expressions. The standard rules of precedence for Boolean evaluation are used. The software ceases to evaluate a Boolean expression…
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A null string is a character string of zero length. Unlike the $Null property that indicates that the value is unknown or unassigned, the null string is a known value. For example, if you have two variables, x and y, both of which are null strings, then the expression x = ” and y ‘abc’…
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Certain characters, such as quotation marks and the backslash, have special functions in the software. If you need to use one of these metacharacters as a literal character in a string, you must “escape” the special function by inserting a backslash ( – Escape) preceding the metacharacter as shown in the following example: ‘This is…
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The result of an arithmetic expression contains as many decimal places as are found in the operands of the expression. If the expression contains several operands with varying numbers of decimal places, the result takes on the number of decimal places found in the operand with the most decimal places. If the result of the…
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