gistfile1.txt

function success = main()
    a = ["hello"; "unsorted"; "world"; "moobar"]
    b = cellstr(a)
    find(ismember(b, 'world'))   %returns 3

    function i = binsearch(array, val, low, high)
      %binary search algorithm for numerics, Usage:
      %myarray = [ 30, 40, 50.15 ];        %already sorted list
      %binsearch(myarray, 30,    1, 3)     %item 30 is in slot 1
      if ( high < low )
        i = 0;
      else
        mid = floor((low + high) / 2);
        if ( array(mid) > val )
          i = binsearch(array, val, low, mid-1);
        elseif ( array(mid) < val )
          i = binsearch(array, val, mid+1, high);
        else
          i = mid;
        endif
      endif
    endfunction

    function i = binsearch_str(array, val, low, high)
      % binary search for strings, usage:
      %myarray2 = [ "abc"; "def"; "ghi"];       #already sorted list
      %binsearch_str(myarray2, "abc", 1, 3)     #item abc is in slot 1
      if ( high < low )
        i = 0;
      else
        mid = floor((low + high) / 2);
        if ( mystrcmp(array(mid, [1:end]), val) == 1 )
          i = binsearch(array, val, low, mid-1);
        elseif ( mystrcmp(array(mid, [1:end]), val) == -1 )
          i = binsearch_str(array, val, mid+1, high);
        else
          i = mid;
        endif
      endif
    endfunction
    function ret = mystrcmp(a, b)
        %this function is just an octave string compare, it's exactly like
        %strcmp(str1,str2) in C, or java.lang.String.compareTo(...) in Java.
        %returns 1 if string a > b
        %returns 0 if string a == b
        %return -1 if string a < b
        letters_gt = gt(a, b);      %list of boolean a > b
        letters_lt = lt(a, b);      %list of boolean a < b
        ret = 0;
        %octave makes us roll our own string compare because
        %strings are arrays of numerics
        len = length(letters_gt);
        for i = 1:len
            if letters_gt(i) > letters_lt(i)
                ret = 1;
                return
            elseif letters_gt(i) < letters_lt(i)
                ret = -1;
                return
            endif
        end;
    endfunction

    %Assuming that myarray is already sorted, (it must be for binary
    %search to finish in logarithmic time `O(log-n))` worst case, then do

    myarray = [ 30, 40, 50.15 ];        %already sorted list
    binsearch(myarray, 30,    1, 3)     %item 30 is in slot 1
    binsearch(myarray, 40,    1, 3)     %item 40 is in slot 2
    binsearch(myarray, 50,    1, 3)     %50 does not exist so return 0
    binsearch(myarray, 50.15, 1, 3)     %50.15 is in slot 3

    myarray = [ 9, 40, -3, 3.14, 20 ];        %not sorted list
    myarray = sort(myarray)

    myarray2 = [ "the"; "cat"; "sat"; "on"; "the"; "mat"];       %not sorted list
    myarray2 = sortrows(myarray2)
end