findFiles

findFiles function check files in a folder looking for files in which the name matches a pattern.

findFiles check files in a folder looking for files in which the name
matches a pattern

The pattern can have Metacharacters like:
\w Any alphabetic, numeric, or underscore character.
\d Any numeric digit; equivalent to [0-9]
+ Get characters 1 or more times consecutively.
Examples:
Suppose we have the following files:
Image2.bmp
Image5.bmp
Image_not_pattern.bmp
Image3.bmp
Image7.bmp
other_stuff.bmp
Image1.bmp
Image4.bmp
Image8.bmp
And we want to select only the "images", our pattern shall be written as:
pattern='image(\d+).bmp'
Note that here we have 1 tokens, which gives us the number of the image.
Executing the command:
fileList = findFiles('C:\whatever\...',pattern);
The output (fileList) will be a cell matrix (7 by 2):

Image2.bmp 2
Image5.bmp 5
Image3.bmp 3
Image7.bmp 7
Image1.bmp 1
Image4.bmp 4
Image8.bmp 8
If desired, you can sort it changing 2nd column from char to number and
using the sortrows command:
char2num
for count1=1:1:size(fileList,2)
fileList{count1,2} = str2num(fileList{count1,2});
end
sortrows(fileList, 2)

A more challenging problem is:
Suppose we have the following files:
itrs3_ab_18_4--1.6e-10delay09443.dat
itrs3_ab_18_4--1e-06delay09517.dat
itrs3_ab_18_4--1e-07delay09716.dat
itrs3_ab_18_4-2e-06delay09490.dat
itrs3_ab_18_4-3e-06delay09521.dat
itrs3_ab_18_4--3e-08delay09511.dat
itrs3_ab_18_4-3e-09delay09681.dat

And we want to select only the files that has a 6 before "delay", our
pattern shall be written as:

pattern='itrs3_ab_(\d+)_4-(|-)(\d+)e-06delay(\d+).dat'

Note that here we have 4 tokens:
The 1st, 3rd and 4th are (\d+), they will read the numbers.
The 2nd is (|-), will check if there is nothing or a minus symbol.

Executing the command:
fileList = findFiles('C:\whatever\...',pattern);

The output (fileList) will be a cell matrix (3 by 4):

itrs3_ab_18_4--1e-06delay09517.dat 18 - 1 09517
itrs3_ab_18_4-2e-06delay09490.dat 18 2 09490
itrs3_ab_18_4-3e-06delay09521.dat 18 2 09521

For more information about tokens, see <a href="matlab:
web('http://www.mathworks.com/help/matlab/matlab_prog/regular-expressions.html')">regular-expressions on Matlab</a>.

See also regexp, dir.