Why is isstr not recommended?

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Josh G.
Josh G. on 25 Jan 2019
Commented: Star Strider on 28 Jan 2019
When using isstr in my code, I get a warning that it is not recommended and I should use ischar instead. But ischar doesn't provide the same functionality as isstr. For a string, ischar returns 0 and isstr returns 1, while for a character array, ischar returns 1 and isstr returns 1. There doesn't seem to be any replacement for isstr that provides the same functionality. Why is this warning displayed?

Accepted Answer

Star Strider
Star Strider on 25 Jan 2019
The string (link) datatype was introduced in R2016b, along with a number of functions to work with it, of which isstring (link) is one. I suspect the recommendations for isstr changed to be compatible with the new datatype, and avoid any ambiguity.
Star Strider
Star Strider on 28 Jan 2019
I don’t believe MathWorks is actually ‘recommending’ one over the other, just doing its best to avoid ambiguity. It very much depends on what you’re testing.
Example —
s = "string!";
c = 'character!';
ischar_test = [ischar(s) ischar(c)]
isstring_test = [isstring(s) isstring(c)]
isstr_test = [isstr(s) isstr(c)]
ischar_test =
1×2 logical array
0 1
isstring_test =
1×2 logical array
1 0
isstr_test =
1×2 logical array
0 1
This also illustrates the problem with isstr.

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