Section: Inspection Functions
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)
kind specification out, in which case
the calling syntax is
y = exist(item)
The return code is one of the following:
item does not exist
item is a variable in the workspace
item is an M file on the search path, a full pathname
to a file, or an ordinary file on your search path
item is a built-in FreeMat function
item is a directory
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.
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) =
0.8887 -0.2749 -0.1202 0.2347 0.2815
-0.9052 0.2688 1.9047 -0.0533 -1.6196
-1.6519 0.1689 0.5134 -0.5795 0.7863
(:,:,2) =
0.8246 -0.5823 -0.6986 0.3591 -2.5987
-0.5022 2.4368 1.2679 -1.4748 -0.4239
-0.9966 -0.5530 -0.3325 2.2984 0.5024
--> b = []
b =
[]
--> who
Variable Name Type Flags Size
a double [3 5 2]
b double [0 0]
--> exist('a')
ans =
1
--> exist('b')
ans =
1
--> exist('c')
ans =
0
-->
quit