MATLAB Programming Fundamentals - MathWorks

(shown here as point A). If all operations in the try block succeed, then execution skips

the catch block entirely and goes to the first line following the end statement (point B).

Specifying the try, catch, and end commands and also the code of the try and catch

blocks on separate lines is recommended. If you combine any of these components on the

same line, separate them with commas:

try, surf, catch ME, ME.stack, end

ans =

file: 'matlabroot\toolbox\matlab\graph3d\surf.m'

name: 'surf'

line: 54

NoteYou cannot define nested functions within a try or catch block.

The Try Block

On execution, your code enters the try block and executes each statement as if it were

part of the regular program. If no errors are encountered, MATLAB skips the catch block

entirely and continues execution following the end statement. If any of the try

statements fail, MATLAB immediately exits the try block, leaving any remaining

statements in that block unexecuted, and enters the catch block.

The Catch Block

The catch command marks the start of a catch block and provides access to a data

structure that contains information about what caused the exception. This is shown as the

variable ME in the preceding pseudocode. This data structure is an object of the MATLAB

MException class. When an exception occurs, MATLAB constructs an instance of this

class and returns it in the catch statement that handles that error.

You are not required to specify any argument with the catch statement. If you do not

need any of the information or methods provided by the MException object, just specify

the catch keyword alone.

The MException object is constructed by internal code in the program that fails. The

object has properties that contain information about the error that can be useful in

determining what happened and how to proceed. The MException object also provides

access to methods that enable you to respond to the exception. See the section on “The

MException Class” on page 26-5 to find out more about the MException class.

26 Error Handling