Why is isstr not recommended?

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Josh G.
Josh G. 2019-1-25
评论： Star Strider 2019-1-28
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?

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Star Strider
Star Strider 2019-1-25
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.
  2 个评论
Josh G.
Josh G. 2019-1-28
I wasn't aware of isstring, but that looks like a better replacement. I wonder why Mathworks recommends ischar though instead of isstring.
Star Strider
Star Strider 2019-1-28
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)]
produces:
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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