How can i compare two strings by their alphabetical order

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

[James Tursa]

Please give a few more examples so we are sure what your function is supposed to do.

[Denememe]

      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

Answer 1

[dpb]

>> '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...

Answer 2

[Jomar Bueyes]

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

Answer 3

[Paul Herselman]

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