lasterr

Last error message

lasterr is not recommended. Use MException instead. For more information, see Version History.

Syntax

msgstr = lasterr [msgstr,errID] = lasterr lasterr('new_msgstr') lasterr('new_msgstr','new_errID') [msgstr,errID] = lasterr('new_msgstr','new_errID')

Description

msgstr = lasterr returns the last error message generated by MATLAB^®.

[msgstr,errID] = lasterr returns the last error in msgstr and its identifier in errID. If the error was not defined with an identifier, lasterr returns an empty character vector for errID. For more information about error identifiers, see MException.

lasterr('new_msgstr') sets the last error message to a new character vector, new_msgstr, so that subsequent invocations of lasterr return the new error message. You can also set the last error to an empty character vector with lasterr('').

lasterr('new_msgstr','new_errID') sets the last error message and error identifier to new_msgstr and new_errID, respectively. Subsequent invocations of lasterr return the new error message and error identifier.

[msgstr,errID] = lasterr('new_msgstr','new_errID') returns the last error message and error identifier, also changing these values so that subsequent invocations of lasterr return the message and identifier specified by new_msgstr and new_errID respectively.

Examples

Example 1

Here is a function that examines the lasterr character vector and displays its own message based on the error that last occurred. This example deals with two cases, each of which is an error that can result from a matrix multiplication:

function matrix_multiply(A,B)
try
   A * B
catch
   errmsg = lasterr;
   if(strfind(errmsg, 'Inner matrix dimensions'))
      disp('** Wrong dimensions for matrix multiply')
   else
      if(strfind(errmsg, 'not defined for variables of class'))
         disp('** Both arguments must be double matrices')
      end
   end
end

If you call this function with matrices that are incompatible for matrix multiplication (e.g., the column dimension of A is not equal to the row dimension of B), MATLAB catches the error and uses lasterr to determine its source:

A = [1  2  3; 6  7  2; 0  -1  5];
B = [9  5  6; 0  4  9];

matrix_multiply(A,B)
** Wrong dimensions for matrix multiply

Example 2

Specify an error identifier and error message with error:

error('MyToolbox:angleTooLarge',... 
      'The angle specified must be less than 90 degrees.');

In your error handling code, use lasterr to determine the error identifier and error message for the failing operation:

[errmsg,errID] = lasterr
errmsg =
   The angle specified must be less than 90 degrees.
errID =
   MyToolbox:angleTooLarge

Extended Capabilities

Thread-Based Environment
Run code in the background using MATLAB® `backgroundPool` or accelerate code with Parallel Computing Toolbox™ `ThreadPool`.

Version History

Introduced before R2006a

collapse all

R2007b: `lasterr` is not recommended

MathWorks^® is gradually transitioning MATLAB error handling to an object-oriented scheme that is based on the MException class. Although support for lasterr is expected to continue, using the static MException.last method of MException is preferable.

Warning

lasterr and MException.last are not guaranteed to always return identical results. For example, MException.last updates its error status only on uncaught errors, where lasterr can update its error status on any error, whether it is caught or not.