ListExists
Indicates whether an element is present in the list and has a value.
Synopsis
ListExists(list,position)
Arguments
| list | An expression that evaluates to a valid list. A Caché list must be created using ListBuild or ListFromString, or extracted from another list using List. |
| position | An integer specifying a position in list (counting from 1). |
Description
The ListExists function returns a value of 1 if the element at the indicated position in the list exists and has a data value. Otherwise ListExists returns zero.
Examples
The following example demonstrates the ListExists function. It defines a six-element list, in which the third and fourth elements do not have a defined value:
Erase Y ' Y is now undefined
myList = ListBuild("Red","Blue",,Y,"Yellow","")
Println ListExists(myList,0) ' 0: positions are numbered from 1
Println ListExists(myList,1) ' 1: "Red"
Println ListExists(myList,2) ' 1: "Blue"
Println ListExists(myList,3) ' 0: missing element
Println ListExists(myList,4) ' 0: undefined element
Println ListExists(myList,5) ' 1: "Yellow"
Println ListExists(myList,6) ' 1: empty string OK
Println ListExists(myList,7) ' 0: beyond end of list
Println ListExists(myList,-1) ' 1: last element in list
See Also
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List function
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ListBuild function
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ListFind function
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ListFromString function
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ListGet function
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ListLength function
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ListNext function
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ListSame function
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ListToString function
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ListValid function
