How can i compare two strings by their alphabetical order

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Denememe
Denememe 2016-12-1
回答： Paul Herselman 2024-1-25
I want to write a function which will compare two strings by their alphabetical order. The function should give an output '-1' if the first string is 'a' and second is 'b'. I couldn't do that with strcmp Thank you
  2 个评论
James Tursa
James Tursa 2016-12-1
Please give a few more examples so we are sure what your function is supposed to do.
Denememe
Denememe 2016-12-1
function output = strCompare(s1,s2)
ls1=length(s1);
ls2=length(s2);
if ls1<ls2
for i=1:ls1
if s1(i)<s2(i)
output = [-1];
elseif s1(i)>s2(i)
output = [1];
else
output = [0];
end
end
elseif ls1>=ls2
for i=1:ls2
if s1(i)<s2(i)
output = [-1];
elseif s1(i)>s2(i)
output = [1];
else
output = [0];
end
end
end
end
I wrote this function but i want to have an output '1' when s1 = 'America' and s2='A' I take '0' when i do that

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回答（3 个）

dpb
dpb 2016-12-1
编辑：Walter Roberson 2016-12-2
>> 'a'-'b'
ans =
-1
>>
may give you some ideas??? Or, instead of reinventing the wheel,
lexcmp from File Exchange probably does what you're looking for...
Jomar Bueyes
Jomar Bueyes 2019-8-23
编辑：Jomar Bueyes 2019-8-23
I know this question is old. But I wrote a the function below that does what Denememe wants.
function seg = arraySortCriterion(a, b)
% arraySortCriterion returns -1, 0, 1 depending of how a,b must be sorted
%
% SYNTAX:
% seg = arraySortCriterion(a, b);
%
% DESCRIPTION:
% seg = arraySortCriterion(a, b);
% Returns;
% -1 if a must precede b when sorted
% 1 if b must precede a when sorted
% 0 if a and b can be in either order
%
% For arrays and strings, the function compares element by element
% until it finds an element such that a(k) ~= b(k) and returns
% -1 if a(k) < b(k)
% 1 if a(k) > b(k)
% If the two strings or arrays are equal up to the length of the
% shortest one, the shorter array or string goes first in when
% sorted. This is consistent with how Matlab, Python, and Perl sort
% this of strings of different lengths that are equal up to the
% length of the shortest one.
% Author/Date
% Jomar Bueyes
%
% Copyright 2019 Jomar Bueyes
Na = numel(a);
Nb = numel(b);
for k = 1:min(Na, Nb)
seg = sign(a(k) - b(k));
if seg ~= 0
return;
end
end
% ..The two strings/arrays are equal up to the length of the shortest one
seg = sign(Na-Nb); % This places the shortest one first.
return
end
Paul Herselman
Paul Herselman 2024-1-25
Here is another alternative, using MatLabs convertCharsToStrings function
convertCharsToStrings('abc') < convertCharsToStrings('def')
or if you want a function:
function [lexicalOrder] = strCmpLikeC(str1, str2)
%[lexicalOrder] = strCmpLikeC(str1, str2)
% a strcmp function like the c language
% inputs: str1 and str2 can be chars or strings
% return 0 if strings match
% return 1 if first non matching character of str1 is lexically greater (in Ascii) than corresponding character in str2
% else return -1
aStr = convertCharsToStrings(str1);
bStr = convertCharsToStrings(str2);
lexicalOrder = 0;
if aStr > bStr
lexicalOrder = 1;
elseif bStr > aStr
lexicalOrder = -1;
end
end

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