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Usage
Tests for the existence of a variable, function, directory
or file. The general syntax for its use is
y = exist(item,kind)
where item is a string containing the name of the item to
look for, and kind is a string indicating the type of the
search. The kind must be one of
* 'builtin' checks for built-in functions
* 'dir' checks for directories
* 'file' checks for files
* 'var' checks for variables
* 'all' checks all possibilities (same as leaving out kind)
You can also leave the kind specification out, in which case
the calling syntax is
y = exist(item)
The return code is one of the following:
* 0 - if item does not exist
* 1 - if item is a variable in the workspace
* 2 - if item is an M file on the search path, a full
pathname to a file, or an ordinary file on your search
path
* 5 - if item is a built-in FreeMat function
* 7 - if item is a directory
Note: previous to version 1.10, exist used a different
notion of existence for variables: a variable was said to
exist if it was defined and non-empty. This test is now
performed by isset.
Example
Some examples of the exist function. Note that generally
exist is used in functions to test for keywords. For
example,
function y = testfunc(a, b, c)
if (~exist('c'))
% c was not defined, so establish a default
c = 13;
end
y = a + b + c;
An example of exist in action.
--> a = randn(3,5,2)
a =
(:,:,1) =
0.7785 0.6357 1.7582 1.5784 -0.8470
0.7235 1.0468 -0.6919 -0.6796 0.4767
0.2100 0.0865 1.5704 -0.1267 2.1381
(:,:,2) =
1.5525 -0.2908 -1.4220 1.1076 0.2419
0.1652 -0.5668 -0.8018 -0.5975 0.8483
0.3147 -0.1109 -0.5203 0.5851 1.1503
--> b = []
b =
[]
--> who
Variable Name Type Flags Size
a double [3x5x2]
b double [0x0]
--> exist('a')
ans =
1
--> exist('b')
ans =
1
--> exist('c')
ans =
0
* FreeMat_Documentation
* Inspection_Functions
* Generated on Thu Jul 25 2013 17:17:38 for FreeMat by
doxygen_ 1.8.1.1
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