dlmread filename not a character vector

Hello, I am having problems using dlm read within a for loop. I would like to define a directory my files are in, the basic name of my files, a sequence of numbers at the end of my filename, and the file extension. An example of the filenames is as follows.

folder1/folder2/folder3/filename_000.txt

folder1/folder2/folder3/filename_001.txt

folder1/folder2/folder3/filename_002.txt

This continues up to n files. I would then like to read each file and take out specific data, hence the dlmread function.

What I have is as follows:

 file_directory = 'folder1/folder2/folder3/';
 file_prefix = 'filename_';
 %My numbers 000, 001, 002, 003, etc. are all contained within an array called:  A
 file_suffix = '.txt';
 for i=1:n   %n for the number of files I want to load
     filename = [file_directory file_prefix A(i) file_suffix];
     temp=dlmread(filename ,'', [17 0 3664 1]);
 end

The code runs until temp=dlmread... wherein it gets an error of, "Filename must be a character vector."

Any way on how to fix this?

[Bob Thompson]

I would try defining the file name as:

filename = strcat('folder1/folder2/folder3/filename_',num2str(A(i)),'.txt');
or
filename = sprintf('folder1/folder2/folder3/filename_%d.txt',A(i));

This will eliminate the need to define the directory and such ahead of time.

Alternatively you can try to use the uigetfile() command. I personally use this option more as it allows me a little more freedom as the script user, and when combined with the directory using fullfile() I can give the directory and all through a basic for loop.

[filenames,filedir] = uigetfile('*.txt','','Multiselect','on')
filepath = fullfile(filedir,filenames);
for i = 1:n
temp = dlmread(filepath(i),'',[17 0 3664 1]);
end

Answer 1

[Mike Hodny]

I figured out the problem. The working for loop is as follows:

 for j=0:files
    filename = [file_folder file_prefix A{1,j+1} file_suffix];
    temp=dlmread(filename,'', [17 0 3664 1]);
 end

Answer 2

[Walter Roberson]

Use fullfile and sprintf together. For the numeric field use a %03d format specification in sprintf