% STRNCMP STRNCMP String Compare Function To Length N 
% 
% Usage
% 
% Compares two strings for equality, but only looks at the
% first N characters from each string.  The general syntax 
% for its use is
% 
%   p = strncmp(x,y,n)
% 
% where x and y are two strings.  Returns true if x
% and y are each at least n characters long, and if the
% first n characters from each string are the same.  Otherwise,
% it returns false.
% In the second form, strncmp can be applied to a cell array of
% strings.  The syntax for this form is
% 
%   p = strncmp(cellstra,cellstrb,n)
% 
% where cellstra and cellstrb are cell arrays of a strings
% to compare.  Also, you can also supply a character matrix as
% an argument to strcmp, in which case it will be converted
% via cellstr (so that trailing spaces are removed), before being
% compared.

function y = strncmp(source,pattern,n)
  if (isstr(source) & isstr(pattern))
    y = strncmp_string_string(source,pattern,n);
  else
    y = strncmp_cell_cell(cellstr(source),cellstr(pattern),n);
  end


function y = strncmp_cell_cell(source,pattern,n)
  if (isscalar(source))
    source = repmat(source,size(pattern));
  end
  if (isscalar(pattern))
    pattern = repmat(pattern,size(source));
  end
  if (numel(source) ~= numel(pattern))
    error('cell array arguments must be the same size')
  end
  y = logical(zeros(size(source)));
  for (i=1:numel(source))
    y(i) = strncmp_string_string(source{i},pattern{i},n);
  end

function z = strncmp_string_string(x,y,n)
  if ((length(x) < n) | (length(y) < n))
    z = logical(0);
  else
    z = strcomp(x(1:n),y(1:n));
  end