Matlab文件读取问题

    很久不用matlab读取文件了，结果最近用matlab中的“dir"函数读取文件夹下面的图像对图像特征进行统计，但是统计的结果与实际情况不符合，刚开始自己一直怀疑是图片的问题，但是经过和同学交流才恍然大悟，当依次遍历文件夹下的文件时，不是按照十进制数字的大小读取，而是

为了能够按照十进制的大小读取同一个文件夹下的文件，需要用sort_nat函数对文件夹下的文件按照文件名的大小进行排序得到一个这样元胞数组

function [cs,index] = sort_nat(c,mode)
%sort_nat: Natural order sort of cell array of strings.
% usage:  [S,INDEX] = sort_nat(C)
%
% where,
%    C is a cell array (vector) of strings to be sorted.
%    S is C, sorted in natural order.
%    INDEX is the sort order such that S = C(INDEX);
%
% Natural order sorting sorts strings containing digits in a way such that
% the numerical value of the digits is taken into account.  It is
% especially useful for sorting file names containing index numbers with
% different numbers of digits.  Often, people will use leading zeros to get
% the right sort order, but with this function you don't have to do that.
% For example, if C = {'file1.txt','file2.txt','file10.txt'}, a normal sort
% will give you
%
%       {'file1.txt'  'file10.txt'  'file2.txt'}
%
% whereas, sort_nat will give you
%
%       {'file1.txt'  'file2.txt'  'file10.txt'}
%
% See also: sort
% Version: 1.4, 22 January 2011
% Author:  Douglas M. Schwarz
% Email:   dmschwarz=ieee*org, dmschwarz=urgrad*rochester*edu
% Real_email = regexprep(Email,{'=','*'},{'@','.'})
% Set default value for mode if necessary.
if nargin < 2
	mode = 'ascend';
end
% Make sure mode is either 'ascend' or 'descend'.
modes = strcmpi(mode,{'ascend','descend'});
is_descend = modes(2);
if ~any(modes)
	error('sort_nat:sortDirection',...
		'sorting direction must be ''ascend'' or ''descend''.')
end
% Replace runs of digits with '0'.
c2 = regexprep(c,'\d+','0');
% Compute char version of c2 and locations of zeros.
s1 = char(c2);
z = s1 == '0';
% Extract the runs of digits and their start and end indices.
[digruns,first,last] = regexp(c,'\d+','match','start','end');
% Create matrix of numerical values of runs of digits and a matrix of the
% number of digits in each run.
num_str = length(c);
max_len = size(s1,2);
num_val = NaN(num_str,max_len);
num_dig = NaN(num_str,max_len);
for i = 1:num_str
	num_val(i,z(i,:)) = sscanf(sprintf('%s ',digruns{i}{:}),'%f');
	num_dig(i,z(i,:)) = last{i} - first{i} + 1;
end
% Find columns that have at least one non-NaN.  Make sure activecols is a
% 1-by-n vector even if n = 0.
activecols = reshape(find(~all(isnan(num_val))),1,[]);
n = length(activecols);
% Compute which columns in the composite matrix get the numbers.
numcols = activecols + (1:2:2*n);
% Compute which columns in the composite matrix get the number of digits.
ndigcols = numcols + 1;
% Compute which columns in the composite matrix get chars.
charcols = true(1,max_len + 2*n);
charcols(numcols) = false;
charcols(ndigcols) = false;
% Create and fill composite matrix, comp.
comp = zeros(num_str,max_len + 2*n);
comp(:,charcols) = double(s1);
comp(:,numcols) = num_val(:,activecols);
comp(:,ndigcols) = num_dig(:,activecols);
% Sort rows of composite matrix and use index to sort c in ascending or
% descending order, depending on mode.
[unused,index] = sortrows(comp);
if is_descend
	index = index(end:-1:1);
end
index = reshape(index,size(c));
cs = c(index);

files = dir(fullfile('C:/Users/123/Desktop/云图/选择/031516251705fenge/','*.jpg'));
imdir=sort_nat({files.name}); 
lengthFiles = length(imdir);
C=[];
for r=1:lengthFiles
    % 读入图像
    imtemp = imread(strcat('C:/Users/123/Desktop/云图/选择/031516251705fenge/',imdir{r}));
end
    

希望自己真的记住了，下次不要再这上面浪费时间了