Overview of the evaluation function in ASP

The

<1>isarray function
Returns a Boolean value that indicates whether a variable is an array. The
Syntax
IsArray (varname)
VarName parameter can be any variable.
Description
The IsArray function returns True if the variable is an array, otherwise the function returns FALSE. Using the IsArray function works well when a variable contains an array. The

<2>isdate function
Returns a Boolean value that indicates whether an expression can be converted to a date. The
Syntax
IsDate (expression)
expression parameter can be any date expression or string expression that can be recognized as a date and time. The

Description
Returns True If the expression is a date or can be legitimately converted to a valid date, otherwise the function returns FALSE. IsDate Valid date range in Microsoft Windows operating system A.D. January 1, 100 to A.D. December 31, 9999; The legal date range varies depending on the operating system. The

<3>isempty function
Returns a Boolean value indicating whether the variable has been initialized. The
Syntax
isempty (expression)
expression parameter can be any expression. However, because IsEmpty is used to determine whether a variable has been initialized, the expression argument is often a variable name. The

Description
Returns True If the variable is not initialized or explicitly set to Empty, otherwise the function returns FALSE. If expression contains more than one variable, the total returns FALSE. The

<4>isnull function
Returns a Boolean value that indicates whether an expression contains no valid data (Null). The
Syntax
IsNull (expression)
expression parameter can be any expression.
Description
If expression is Null, IsNull returns True, that is, the expression does not contain valid data, or IsNull returns FALSE. If the expression is composed of multiple variables, the values in any constituent variables of the expression Null causes the entire expression to return True. A
Null value indicates that the variable does not contain valid data. Null differs from Empty, which indicates that the variable was uninitialized. Null is also different from a 0-length string (""), and a 0-length string often refers to an empty string. The

focuses on using the IsNull function to determine whether an expression contains a Null value. In some cases, you want the expression to be value True, such as Ifvar=null and Ifvar<>null, but they are usually always False. This is because any expression containing a null itself is null, so the expression evaluates to False. The

<5>isnumeric function
Returns a Boolean value that indicates whether the expression's value is a number. The
Syntax
isnumeric (expression)
expression parameter can be any expression.
Description
The IsNumeric function returns True if the entire expression is recognized as a number, otherwise the function returns FALSE.
If expression is a date expression, the IsNumeric function returns FALSE. The

<6>isobject function
Returns a Boolean value indicating whether an expression refers to a valid Automation object. The
Syntax
IsObject (expression)
expression parameter can be any expression. The

Description
Returns True If expression is an object subtype variable or user-defined isobject, otherwise the function returns FALSE.