MATLAB Programming

12 Programming Tips
Variables
This section covers the following topics:
• “Rules for Variable Names” on page 12-26
• “Making Sure Variable Names Are Valid” on page 12-26
• “Don’t Use Function Names for Variables” on page 12-27
• “Checking for Reserved Keywords” on page 12-27
• “Avoid Using i and j for Variables” on page 12-28
• “Avoid Overwriting Variables in Scripts” on page 12-28
• “Persistent Variables” on page 12-28
• “Protecting Persistent Variables” on page 12-28
• “Global Variables” on page 12-29
Rules for Variable Names
Although variable names can be of any length, MATLAB uses only the first
N characters of the name, (where N is the number returned by the function
namelengthmax), and ignores the rest. Hence, it is important to make
each variable name unique in the first N characters to enable MATLAB to
distinguish variables. Also note that variable names are case sensitive.
N = namelengthmax
N =
63
For more information: See “Naming Variables” on page 3-7 in the MATLAB
Programming documentation.
Making Sure Variable Names Are Valid
Before using a new variable name, you can check to see if it is valid with the
isvarname function. Note that isvarname does not consider names longer
than namelengthmax characters to be valid.
For example, the following name cannot be used for a variable since it begins
with a number.
12-26