Last error message and related information
s = lasterror
s = lasterror(err)
s = lasterror('reset')
s = lasterror returns
s containing information about the
most recent error issued by the MATLAB® software. The return structure
contains the following fields:
Character array containing the text of the error message.
Character array containing the message identifier of
the error message. If the last error issued by MATLAB had no
message identifier, then the
Structure providing information on the location of the
error. The structure has fields
The fields of the structure returned in
Name of the file in which the function generating the error appears. This field is the empty string if there is no file.
Name of the function in which the error occurred. If
this is the primary function in the file, and the function name differs
from the file name,
Line number of the file at which the error occurred.
See Message Identifiers in the MATLAB Programming Fundamentals documentation for more information on the syntax and usage of message identifiers.
s = lasterror(err) sets
the last error information to the error message and identifier specified
in the structure
err. Subsequent invocations of
this new error information. The optional return structure
information on the previous error.
s = lasterror('reset') sets
the last error information to the default state. In this state, the
of the return structure are empty strings, and the
is a 0-by-1 structure.
Save the following MATLAB code in a file called
function y = average(x) % AVERAGE Mean of vector elements. % AVERAGE(X), where X is a vector, is the mean of vector elements. % Nonvector input results in an error. check_inputs(x) y = sum(x)/length(x); % The actual computation function check_inputs(x) [m,n] = size(x); if (~((m == 1) || (n == 1)) || (m == 1 && n == 1)) error('AVG:NotAVector', 'Input must be a vector.') end
Now run the function. Because this function requires vector
input, passing a scalar value to it forces an error. The error occurs
average(200) Error using average>check_inputs (line 11) Input must be a vector. Error in average (line 5) check_inputs(x)
Get the three fields from
err = lasterror err = message: [1x61 char] identifier: 'AVG:NotAVector' stack: [2x1 struct]
Display the text of the error message:
msg = err.message msg = Error using average>check_inputs (line 11) Input must be a vector.
Display the fields containing the
a 2-by-1 structure because it provides information on the failing
check_inputs and also the outer, primary
st1 = err.stack(1,1) st1 = file: 'd:\matlab_test\average.m' name: 'check_inputs' line: 11 st2 = err.stack(2,1) st2 = file: 'd:\matlab_test\average.m' name: 'average' line: 5
As a rule, the name of your primary function should be the same
as the name of the file that contains that function. If these names
differ, MATLAB uses the file name in the
try do_something catch do_cleanup rethrow(lasterror) end
MathWorks® is gradually transitioning MATLAB error
handling to an object-oriented scheme that is based on the
MException class. Although support
lasterror is expected to continue, using
MException is preferable.