Switch does not work in GUI

Question

Lawson Hoover 2012-11-9

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/53346-switch-does-not-work-in-gui

While running my code through a GUI the SWITCH function does that detect the cases, or maybe it just jumps to the bottom otherwise every time.

contents = cellstr(get(S.element,'String'));
t1 = contents{get(S.element,'Value')};
t = char(t1);
contents = cellstr(get(S.mass,'String'));
u1 = contents{get(S.mass,'Value')};
u = char(u1);
contents = cellstr(get(S.volume,'String'));
v1 = contents{get(S.volume,'Value')};
v = char(v1);
global dens 
switch t 
    case strcmp(t,'Scandium')
        dens = 2.989;
    case strcmp(t,'Yttrium')
        dens = 4.469;
    case strcmp(t,'Selenium')
        dens = 4.809;
    case strcmp(t,'Krypton')
        dens = .003733;
    case strcmp(t,'Neodymium')
        dens = 7.007;
    case strcmp(t,'Antimony')
        dens = 6.685;
    case strcmp(t,'Astatine')
        dens = 7;
    otherwise
        dens = 8.55;
end

Every time it jumps to the other wise option of -- dens = 8.55.

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Answer 1

Walter Roberson 2012-11-9

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在 MATLAB Online 中打开

You need to convert

switch t

to

switch true

because the value that you give in the "switch" is compared to the values of the "case" statements, and the values of the case statements are the result of the strcmp() and hence are true or false.

Alternately, leave it as "switch t" and remove the strcmp()

case 'Yttrium'

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Walter Roberson 2012-11-10

编辑：Walter Roberson 2012-11-10

在 MATLAB Online 中打开

Consider this:

densities = struct('scandium', 2.989', 'yttrium', 4.469, 'selenium', 4.809);
tl = lower(t);
if isfield(densities,tl)
  dens = densities.(tl);
else
  error('not a known element')
end

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Answer 2

Image Analyst 2012-11-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/53346-switch-does-not-work-in-gui#answer_64963

在 MATLAB Online 中打开

Try it like this:

switch lower(t) 
    case 'scandium'
        dens = 2.989;
    case 'yttrium'
        dens = 4.469;
    case 'selenium'
        dens = 4.809;
    case 'krypton'
        dens = .003733;
    case 'neodymium'
        dens = 7.007;
    case 'antimony'
        dens = 6.685;
    case 'astatine'
        dens = 7;
    otherwise
        dens = 8.55;
end