Find files of a certain extension and populate a structure field with those file names.

I have a directory with multiple .txt files. I want find all those .txt files and create a structure field with the names of those files. I've tried the following:

>> dir(strcat(pwd,'\','*.txt'))

Test_1.txt  Test_2.txt  Test_3.txt  

>> struct1.file_names = dir(strcat(pwd,'\','*.txt'))

struct1 = 

  struct with fields:

    file_names: [3×1 struct]

>> struct1.file_names

ans = 

  3×1 struct array with fields:

    name
    folder
    date
    bytes
    isdir
    datenum

I don't understand why these three commands:

dir(strcat(pwd,'\','*.txt'))

struct1.file_names = dir(strcat(pwd,'\','*.txt'))

struct1.file_names

produce different outputs. I also don't know how to populate struct1.file_names with the names of my .txt files. Can someone please help?

Answer 1

[Scott MacKenzie]

Your second command is wrong. The dir command returns a structure. You don't need to append ".file_names". The filenames are part of the structure returned by dir. Try this:

struct1 = dir(strcat(pwd,'\','*.txt')) % show the structure returned by dir
struct1.name                           % show the filenames within the structure returned by dir

[Allen Hammack]

Thank you! Using your suggestion, I was able to get what I need.

I ended up using part of the solution provided by "-" below.

[Scott MacKenzie]

@Allen Hammack, you're welcome. Good luck.

Answer 2

[Voss]

dir() with no output argument (i.e., not assigning the result to any variable) displays the result to the command line.

S = dir() with an output argument (i.e., assigning to the variable S in this case) gives you an array of structs, each element of which corresponds to one item (that is, one file or folder) and contains the file (or folder) name as well as other information.

Assigning the output of your dir() call (rewritten here to use fullfile()) to a variable seems like it will give you the information you want

struct1 = dir(fullfile(pwd(),'*.txt'))

struct1 = 

  0×1 empty struct array with fields:

    name
    folder
    date
    bytes
    isdir
    datenum

names = {struct1.name}

names =

  0×0 empty cell array

struct1 = dir() % get everything, not just .txt files

struct1 = 2×1 struct array with fields:
    name
    folder
    date
    bytes
    isdir
    datenum

names = {struct1.name}

names = 1×2 cell array
    {'.'}    {'..'}

[Allen Hammack]

Thank you! Your solution was helpful! I ended up using part of it to get what I needed. I mainly used the solution that was submitted before yours, so I accepted that one. Thanks!

[Voss]

You're welcome!