Switch problem

Question

Benaiah 2011-7-30

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12706-switch-problem

Hello, I'm currently learning MATLAB, and the code from one question of the week 5 lab doesn't work. It returns me the error "??? SWITCH expression must be a scalar or string constant."

The code is below:

names = [{'Sam','Jim','Tom','Joe','Kai','Zoe','Jan','Pam','Bob','Ann'}];

Names = sort(names);

MarkUpdater = menu('please select a name from the menu: ',Names)

for i=1: length(Names)

switch Names

    case 1
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markAnn = mark-1;
    case 2
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markBob = mark-1;
    case 3
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markJan = mark-1;
    case 4
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markJim = mark-1;
    case 5
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markJoe = mark-1;
    case 6
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markKai = mark-1;
    case 7
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markPam = mark-1;
    case 8
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markSam = mark-1;
    case 9
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markTom = mark-1;
    case 10
        mark=menu('please select the mark: ', ...
                  '0','1','2','3','4','5','6','7','8','9','10')
        markZoe = mark-1;

end

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Answer 1

Walter Roberson 2011-7-30

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/12706-switch-problem#answer_17383

Instead of switching on Names, you need to switch on MarkUpdater since that is your numeric value.

(There are, of course, much better ways to write that code, but presumably the lab will lead you through them.)

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Benaiah 2011-7-30

When i changed "switch Names" to "switch MarkUpdater", it just repeated loading the mark selection menu for the name i selected 10 times, then popped up an error saying "??? Undefined function or variable 'MarkBob' if i selected Ann as the name.