<1> Isarray function
Returns the Boolean value indicates whether a variable is an array.
grammar
Isarray (varName)
VarName parameters can be any variable.
Description
If the variable is an array, the IsarRay function returns true; otherwise, the function returns false. When there is an array in the variable, use the isarray function is very effective.
<2> isdate function
Returns the Boolean value indicates whether an expression can be converted to a date.
grammar
Isdate (Expression)
The Expression parameter can be any date express or string expression that can be identified as a date and time.
Description
If the expression is a date or legally converted to a valid date, the isdate function returns true; otherwise the function returns false. In the Microsoft Windows operating system, the effective date ranges to January 1, 1899, to 31 December 31, 9999; the legal date range is different from the operating system.
<3> iSempty function
Returns the Boolean value indicates whether the variable is initialized.
grammar
ISempty (Expression)
The Expression parameter can be any expression. However, since iSempty is used to determine if a variable is initialized, the Expression parameter is often a variable name.
Description
If the variable is not initialized or explicitly set to EMPTY, the function iSempty returns true; otherwise the function returns false. If the expression contains more than one variable, always returns false.
<4> isnull function
Returns the Boolean value indicating whether the expression does not contain any valid data (NULL).
grammar
Isnull (Expression)
The Expression parameter can be any expression.
Description
If Expression is NULL, isnull returns true, ie the expression does not contain valid data, otherwise ISNULL returns false. If Expression consists of multiple variables, NULL in any component variable of the expression will return the entire expression.
NULL value indicates that the variable does not contain valid data. NULL is different from EMPTY, and the latter points out that the variable is not initialized. NULL and zero length string ("") are also different, and zero length strings tend to refer to an empty string.
The focus uses the isnull function to determine if the expression contains NULL values. In some cases, you want to make the expression value true, such as ifvar = null, and ifvar <> NULL, but they are usually false. This is because any expression containing NULL itself is NULL, so the result of the expression is false.
<5> IsNumeric function
Returns the Boolean value indicates whether the value of the expression is a number.
grammar
IsNumeric (Expression)
The Expression parameter can be any expression.
Description
If the entire expression is identified as a number, the ISNUMERIC function returns true; otherwise the function returns false.
If Expression is a date expression, the ISNUMERIC function returns false.
<6> IsObject function
Returns the Boolean value indicates whether the expression is a valid Automation object.
grammar
IsObject (Expression)
The Expression parameter can be any expression.
Description
If Expression is an Object subtype variable or a user-defined object, isobject returns true; otherwise the function returns false.
