exist (MathScript RT Module Function)

LabVIEW 2012 MathScript RT模块帮助

版本日期:June 2012

产品编号:373123C-0118

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(仅限Windows)

Owning Class: membership

Requires: MathScript RT Module

Syntax

c = exist(a)

c = exist(a, option)

Description

Determines whether a variable, file, LabVIEW MathScript function, or directory exists.

Examples

Inputs

Name Description
a Specifies the name of the variable, file, function, or directory that you want to determine exists. a is a string.
option Specifies the type of item for which you want to search. option is a string that accepts the following values.

'dir' Checks for directories.
'file' Checks for files or directories.
'function' Checks for MathScript functions. LabVIEW does not search for MathScript functions that you define.
'var' Checks for variables.

Outputs

Name Description
c Determines whether a exists. c is an integer that can return the following values.

0 a does not exist.
1 a is a variable in use.
2 a is an existing file.
5 a is a MathScript function.
7 a is an existing directory.

Details

The following table lists the support characteristics of this function.

Causes reduced performance (warning glyph) Yes
Supported in the LabVIEW Run-Time Engine No
Supported on RT targets No

Examples

A = 'I do exist'
C = exist('A')

Related Topics

dir
is_empty

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