I need help with a switch case and it only comes up with an array of zeros

Question

Nicholas Carlson 2015-10-19

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https://ww2.mathworks.cn/matlabcentral/answers/249376-i-need-help-with-a-switch-case-and-it-only-comes-up-with-an-array-of-zeros

评论： Walter Roberson 2015-10-19

Days_into_Month = zeros(n,1);
Month = char(Month(1:n,1));
for d = (1:n)'
switch Month
    case {'Jan'}
        Days_into_Month(d,1) = {Total_Days(d,1) + 6};
    case {'Feb'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 24};
    case {'Mar'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 53};
    case {'Apr'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 84};
    case {'May'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 114};
    case {'Jun'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 145};
    case {'Jul'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 175};
    case {'Aug'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 206};
    case {'Sep'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 237};
    case {'Oct'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 267};
    case {'Nov'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 298};
    case {'Dec'}
        Days_into_Month(d,1) = {Total_Days(d,1) - 328};
    case {'Ja_'}            
        Days_into_Month(d,1) = {Total_Days(d,1) - 359};
        Actual_Year = Actual_Year + 1;
end
end

I need to find the date for each month in this matrix.

Month =
Mar
Dec
Oct
Oct
May
Jul
Dec

But it only shows up with zeros

Days_into_Month =
       0
       0
       0
       0
       0
       0
       0

My total days into the year is this and it starts from January 6th.

Total_Days =
      61
     344
     296
     289
     132
     195
     352

Also n = 7

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Answer 1

Walter Roberson 2015-10-19

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You are constructing Month as a column array, not as a row vector.

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Nicholas Carlson 2015-10-19

I want it to be a column array

Walter Roberson 2015-10-19

在 MATLAB Online 中打开

I am going to invoke my Mind Reading Toolbox here and say that you needlessly make your cell array Month into an n x 3 character array Month and that now you are comparing the entire n x 3 character array in a switch. If I am correct then you need to change

switch Month

to

switch Month(d,:)

and live with the consequences if any of the entries was not exactly the same length as the others.

However, what you should have done instead is not used char() and instead should have used

switch Month{d}

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