How can I iterate over files in a given directory?

Python 3.6 version of the above answer, using os - assuming that you have the directory path as a str object in a variable called directory_in_str:

import os

directory = os.fsencode(directory_in_str)
    
for file in os.listdir(directory):
    filename = os.fsdecode(file)
    if filename.endswith(".asm") or filename.endswith(".py"): 
        # print(os.path.join(directory, filename))
        continue
    else:
        continue

Or recursively, using pathlib:

from pathlib import Path

pathlist = Path(directory_in_str).glob('**/*.asm')
for path in pathlist:
    # because path is object not string
    path_in_str = str(path)   
    # print(path_in_str)

• Use rglob to replace glob('**/*.asm') with rglob('*.asm')
  • This is like calling Path.glob() with '**/' added in front of the given relative pattern:

from pathlib import Path

pathlist = Path(directory_in_str).rglob('*.asm')
for path in pathlist:
    # because path is object not string
    path_in_str = str(path)
    # print(path_in_str)

Original answer:

import os

for filename in os.listdir("/path/to/dir/"):
    if filename.endswith(".asm") or filename.endswith(".py"): 
        # print(os.path.join(directory, filename))
        continue
    else:
        continue

This will iterate over all descendant files, not just the immediate children of the directory:

import os

for subdir, dirs, files in os.walk(rootdir):
    for file in files:
        #print os.path.join(subdir, file)
        filepath = subdir + os.sep + file

        if filepath.endswith(".asm"):
            print (filepath)

You can try using glob module:

import glob

for filepath in glob.iglob('my_dir/*.asm'):
    print(filepath)

and since Python 3.5 you can search subdirectories as well:

glob.glob('**/*.txt', recursive=True) # => ['2.txt', 'sub/3.txt']

From the docs:

The glob module finds all the pathnames matching a specified pattern according to the rules used by the Unix shell, although results are returned in arbitrary order. No tilde expansion is done, but *, ?, and character ranges expressed with [] will be correctly matched.

Python 3.4 and later offer pathlib in the standard library. You could do:

from pathlib import Path

asm_pths = [pth for pth in Path.cwd().iterdir()
            if pth.suffix == '.asm']

Or if you don't like list comprehensions:

asm_paths = []
for pth in Path.cwd().iterdir():
    if pth.suffix == '.asm':
        asm_pths.append(pth)

Path objects can easily be converted to strings.