comparing strings in alphabetical order

Question

Ella Yeo 2019-5-29

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回答： Guillaume 2019-5-29

I'm trying to see the which of the input of 2strings(x1,x2) come first alphabetically.(e.g if x1 comes first it will return 1, if x2 comes first it will return -1..)

they need to be in a same length otherwise it doesn't work which is why I did 'MaxLength'.Also I got rid of the blanks in between if it's a sentence.

but I'm trying to compare the ASCII code of each string (a=97) and see which one comes first.

i did this so far but it just won't work.

x1= lower(input('Enter a string: ','s'));
x2= lower(input('Enter a string: ','s'));
x1 = strrep(x1,' ','')
x2 = strrep(x2,' ','')%string replacement
x1_d=double(x1)
x2_d=double(x2)
x1_length=length(x1)
x2_length=length(x2)
maxLength = max([length(x1_d), length(x2_d)])
x1_d(length(x1_d)+1:maxLength) = 0
x2_d(length(x2_d)+1:maxLength) = 0
if x1_d<x1_d
disp('x1 alphabetically procedure x2')
elseif x1_d>x2_d
disp('x2 alpha x1')
else
disp('same')
end

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Stephen23 2019-5-29

编辑：Stephen23 2019-5-29

"they need to be in a same length otherwise it doesn't work..."

Because lt operates element-wise. More specifically it follows these rules:

https://www.mathworks.com/help/matlab/matlab_prog/compatible-array-sizes-for-basic-operations.html

You also need to read the if documentation carefully, to know how it behaves with a non-scalar condition.

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Answer 1

Stephen23 2019-5-29

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Simpler and more robust:

S1 = 'banana';
S2 = 'apple';
[~,X] = sort({S1,S2})
Z = diff(X)

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Ella Yeo 2019-5-29

Thank you,

but what if the user entered the exact same word?

Stephen23 2019-5-29

编辑：Stephen23 2019-5-29

在 MATLAB Online 中打开

"but what if the user entered the exact same word?"

Z = diff(X) * ~strcmp(S1,S2)

returns 0 if the words are the same, otherwise -1 or +1. Or you could use an if:

if strcmp(S1,S2)
...
else
...
end

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Answer 2

Guillaume 2019-5-29

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https://ww2.mathworks.cn/matlabcentral/answers/464681-comparing-strings-in-alphabetical-order#answer_377135

在 MATLAB Online 中打开

Even simpler, use strings instead of char vector. Comparison operators work on the whole string instead of on characters

S1 = "banana"
S2 = "apple"
S1 < S2     %returns false
S2 == S2    %returns true

So with your code:

x1 = lower(input('Enter a string: ','s'));
x2 = lower(input('Enter a string: ','s'));
x1 = string(x1);
x2 = string(x2);
if x1 < x2
    disp('x1 is before x2 alphabetically')
elseif x1 == x2
    disp('x1 and x2 are identical')
else
    disp('x1 is after x2 alphabetically')
end