> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/f/file_extension_is_in_extensions_list.md).

# File extension is in extensions list

```ruby
func check_extension(filename, extensions) {
    filename ~~ Regex('\.(' + extensions.map { .escape }.join('|') + ')\z', :i)
}
```

Testing:

```ruby
var extensions = ['zip', 'rar', '7z', 'gz', 'archive', 'A##', 'tar.bz2']
 
var files = [
    'MyData.a##', 'MyData.tar.Gz', 'MyData.gzip', 'MyData.7z.backup',
    'MyData...', 'MyData', 'MyData_v1.0.tar.bz2', 'MyData_v1.0.bz2'
]
 
for file in files {
    printf("%-19s - %s\n", file, check_extension(file, extensions))
}
```

#### Output:

```
MyData.a##          - true
MyData.tar.Gz       - true
MyData.gzip         - false
MyData.7z.backup    - false
MyData...           - false
MyData              - false
MyData_v1.0.tar.bz2 - true
MyData_v1.0.bz2     - false
```