# Clarification about using only the first 'namelengthmax' characters of the name

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Bandar 2019 年 12 月 30 日

In Matlab documentation, it states the following
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.
In my machine, N = 63. But if I attempt to use the following code:
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa=5
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab=6
Matlab did indeed create two variables which contradicts what mentioned in the documentation. Any clarifications!

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### 採用された回答

Image Analyst 2019 年 12 月 30 日
How did you figure out N? Anyway, your variable length is 61, which is not more than 63 so you'll be okay.
alen = length('Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa')
blen = length('Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab')
alen =
61
blen =
61
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Adam Danz 2019 年 12 月 30 日

l = namelengthmax provides the maximum variable name length.
If the first l characters of two variable names are the same, the second one will overwrite the first.
Here are two variable names that are 64 characters long and only differ by the 64th character
clear
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = 1;
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab = 0;
The result is a warning. Both variable names are truncated to 63 characters and the 2nd one overwrites the first.
Warning: 'Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa' exceeds the MATLAB maximum name length of 63
characters and will be truncated to 'Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'.
Warning: 'Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaab' exceeds the MATLAB maximum name length of 63
characters and will be truncated to 'Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'.
List all variables in workspace
who()
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

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