save does not recognize text scalar

33 次查看（过去 30 天）
Richard
Richard 2025-7-24
评论： Walter Roberson 2025-7-25
The following code snippet fails unexpectedly:
clear;
myFilename = 'SavedData';
mustBeTextScalar(myFilename); % Throws exception if not true.
x = 3;
save(myFilename, x);
The variable myFilename passes the mustBeTextScalar as expected. However, the save command fails with the message
Error using save
Argument must be a text scalar.
Error in
saveTest (line 5)
save(myFilename, x);
^^^^^^^^^^^^^^^^^^^
QUESTION: Why does save not see myFilename as a text scalar, even though mustBeTextScalar passes it?
[MATLAB Version: 25.1.0.2943329 (R2025a)]

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采纳的回答

Fangjun Jiang
Fangjun Jiang 2025-7-24
编辑：Fangjun Jiang 2025-7-24
It is not about the variable name myFilename.
save(myFilename)
or
save(myFilename,'x')
  4 个评论
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Stephen23
Stephen23 2025-7-25
"...But in doing so it would have lost the name of the numeric scalar and would only have its value. This is why save() needs text vectors containing the names of variables to be saved, instead of needing the content of those variables."
Yet TABLE manages to do this, so it turns out that functions do not "need" text inputs like this.
Walter Roberson
Walter Roberson 2025-7-25
Ran in:
Well, table() uses inputname under the hood, and invents variable names for cases where expressions were passed. save() does not have the luxary of being able to invent variable names.
x = [1;2;3];
table(x, [4;5;6], +x)
ans = 3×3 table
x Var2 Var3 _ ____ ____ 1 4 1 2 5 2 3 6 3
... variable names are used where inputname() is able to figure them out, and otherwise variable names are invented for expressions.

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