MATLAB Programming Fundamentals - MathWorks

Check Variable Scope in Editor

In this section...

“Use Automatic Function and Variable Highlighting” on page 20-16

“Example of Using Automatic Function and Variable Highlighting” on page 20-17

Scoping issues can be the source of some coding problems. For instance, if you are

unaware that nested functions share a particular variable, the results of running your

code might not be as you expect. Similarly, mistakes in usage of local, global, and

persistent variables can cause unexpected results.

The Code Analyzer does not always indicate scoping issues because sharing a variable

across functions is not an error—it may be your intent. Use MATLAB function and

variable highlighting features to identify when and where your code uses functions and

variables. If you have an active Internet connection, you can watch the Variable and

Function Highlighting video for an overview of the major features.

For conceptual information on nested functions and the various types of MATLAB

variables, see “Sharing Variables Between Parent and Nested Functions” on page 20-33

and “Share Data Between Workspaces” on page 20-11.

Use Automatic Function and Variable Highlighting

By default, the Editor indicates functions, local variables, and variables with shared scope

in various shades of blue. Variables with shared scope include: global variables on page

20-13, persistent variables on page 20-12, and variables within nested functions. (For

more information, see “Nested Functions” on page 20-12.)

To enable and disable highlighting or to change the colors, click Preferences and

select MATLAB > Colors > Programming tools. In MATLAB Online, highlighting is

enabled by default and changing the preferences for highlighting is not available.

By default, the Editor:

• Highlights all instances of a given function or local variable in sky blue when you place
  the cursor within a function or variable name. For instance:

20 Function Basics