How to Get an Extension From A String Filename In Erlang?

In Erlang, you can get the extension from a string filename using the following steps:

1. Start by importing the file library module with the following line of code:

1

-include_lib("kernel/include/file.hrl").

1. Define a function that takes a filename as a string parameter and returns its extension:

1
2
3
4
5

get_extension(FileName) ->
    case filename:split_extension(FileName) of
        {Base, Extension} -> Extension;
        _ -> ""
    end.

1. The filename:split_extension/1 function splits the filename into a base name and an extension. If an extension exists, it will be returned. Otherwise, an empty string will be returned.
2. To use the get_extension/1 function, simply call it with a filename as a string:

1
2
3

FileName = "example.txt",
Extension = get_extension(FileName),
io:format("Extension: ~s~n", [Extension]).

In this example, the filename "example.txt" is passed to the get_extension/1 function, and the extension "txt" will be printed using io:format/2.

Remember to handle the case where the filename has no extension by checking for an empty string.

Best Erlang Books to Read in 2024

1

Rating is 5 out of 5

Handbook of Neuroevolution Through Erlang

Get Book Now

2

Rating is 4.9 out of 5

Designing for Scalability with Erlang/OTP: Implement Robust, Fault-Tolerant Systems

Get Book Now

3

Rating is 4.8 out of 5

Learn You Some Erlang for Great Good!: A Beginner's Guide

Get Book Now

4

Rating is 4.7 out of 5

Erlang Programming: A Concurrent Approach to Software Development

Get Book Now

5

Rating is 4.6 out of 5

Introducing Erlang: Getting Started in Functional Programming

Get Book Now

6

Rating is 4.5 out of 5

Erlang and OTP in Action

Get Book Now

7

Rating is 4.4 out of 5

Programming Erlang: Software for a Concurrent World

Get Book Now

8

Rating is 4.3 out of 5

Programming Erlang: Software for a Concurrent World (Pragmatic Programmers)

Get Book Now

How to get the last component of a file extension in Erlang?

To get the last component of a file extension in Erlang, you can use the filelib module's splitext/1 function. Here's an example:

1
2
3
4
5
6
7

-module(file_extension).
-export([get_last_component/1]).

get_last_component(FilePath) ->
    {_, Extension} = filelib:splitext(FilePath),
    lists:last(string:tokens(Extension, ".")).

In this example, the get_last_component/1 function takes a file path as input and returns the last component of the file extension.

First, the splitext/1 function splits the file path into a tuple of base name and extension. Then, the extension is tokenized using the string:tokens/2 function, splitting it into a list of components. Finally, the lists:last/1 function is used to get the last component from the list.

Here's an example of how you can use this function:

1
2

1> file_extension:get_last_component("/path/to/file.tar.gz").
"gz"

In this example, the function returns "gz" as the last component of the file extension.

How to check if a filename has a valid extension in Erlang?

To check if a filename has a valid extension in Erlang, you can use pattern matching and regular expressions. Here's an example function that checks if a file name has a valid extension:

1
2
3
4
5
6
7
8

-module(filename_check).
-export([has_valid_extension/1]).

has_valid_extension(Filename) ->
    case re:run(Filename, "\\.[a-zA-Z0-9]+$", [{capture, none}]) of
        nomatch -> false;  %% No valid extension found
        _ -> true
    end.

In this function, the regular expression "\\.[a-zA-Z0-9]+$" matches a dot followed by one or more alphanumeric characters at the end of the string. It uses the re:run/3 function to check if the regular expression matches the given filename. If it doesn't match, nomatch is returned, indicating that the filename doesn't have a valid extension. If it matches, _ (a wildcard) is returned, indicating that the filename has a valid extension.

Here's an example usage:

1
2
3
4

1> filename_check:has_valid_extension("example.txt").
true
2> filename_check:has_valid_extension("example").
false

In the first example, the filename "example.txt" has a valid extension, so the function returns true. In the second example, the filename "example" doesn't have a valid extension, so the function returns false.

How to retrieve the file name without the extension in Erlang?

To retrieve the file name without the extension in Erlang, you can use the filename:basename/1 function from the filename module along with some string manipulation functions. Here is an example:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

-module(file_utils).

-export([get_filename_without_extension/1]).

get_filename_without_extension(FilePath) ->
    {ok, FileName, _} = file:consult_filename(FilePath),
    BaseName = filename:basename(FileName),
    remove_extension(BaseName).

remove_extension(FileName) ->
    case string:rfind(FileName, ".") of
        {match, Index} ->
            string:substr(FileName, 1, Index-1);
        nomatch ->
            FileName
    end.

In the above code, the get_filename_without_extension/1 function first uses file:consult_filename/1 to get the file name from the provided file path. Then, it uses filename:basename/1 to remove the directory prefixes from the file name. Finally, the remove_extension/1 function is used to remove the extension from the file name by finding the last occurrence of "." using string:rfind/2 and extracting the substring before it using string:substr/3.

Here is an example usage:

1
2

1> file_utils:get_filename_without_extension("/path/to/file.txt").
"file"

This will return the file name "file" without the extension ".txt".

What is the maximum length limit for a file extension in Erlang?

In Erlang, there is no maximum length limit for a file extension. File extensions are simply part of the file name and can be any length, as long as the overall file name does not exceed the maximum file name length imposed by the operating system. The maximum file name length varies depending on the operating system and file system being used.

What are the common file extensions used in Erlang?

The common file extensions used in Erlang are:

1. .erl - This is the file extension for Erlang source code files. It contains the code written in the Erlang programming language.
2. .hrl - This file extension is used for Erlang header files. Header files contain included libraries and definitions, which are used by Erlang source code files.
3. .beam - After compiling Erlang source code files, the resulting binaries are stored with the .beam file extension. These files can be executed by the Erlang Virtual Machine (BEAM).
4. .yrl - This extension is used for Erlang Yecc parser files. Yecc is a parser generator in Erlang, and these files contain parser specifications.
5. .app - Erlang applications are packaged and deployed using .app files. These files contain metadata and configuration information about the Erlang application.
6. .conf - Configuration files in Erlang often use the .conf extension. These files contain settings and preferences for applications or systems.
7. .sml - Some Erlang projects may include Standard ML (SML) files, which have the .sml extension. SML is another functional programming language that can be used alongside Erlang.

Please note that these are some common file extensions used in Erlang, but there might be additional or project-specific file extensions depending on the specific use case or framework being utilized.