Alright, let's break down why you're hitting this error when specifying a file path, while another method works perfectly. Here are the most common issues and straightforward fixes:

1. Your relative path doesn't match the current working directory #

When you use just 'pprog.txt', Python looks for the file in the current working directory (the folder your script is running from)—not necessarily the folder where your script file is saved.

• To check what your current working directory is, run this quick snippet:

  import os
  print(os.getcwd())
  

• Adjust the path based on where your file actually lives:
  • If the file is one folder above your working directory: '../pprog.txt'
  • If it's in a subfolder: './my_files/pprog.txt'
  • For absolute reliability, use an absolute path (no guesswork involved):

    # Linux/macOS example
    with open('/home/your_username/Documents/pprog.txt', 'r') as file:
        content = file.read()
    # Windows example (use forward slashes or double backslashes)
    with open('C:/Users/your_username/Documents/pprog.txt', 'r') as file:
        content = file.read()
    

2. Typos or case sensitivity got you #

It's easy to misspell a filename, or overlook case differences that matter:

• On Linux and macOS, filenames are case-sensitive: pprog.txt ≠ PPROG.txt
• Even on Windows (case-insensitive by default), hidden file extensions can trick you—like saving a file as pprog.txt.txt without realizing it.

Double-check the exact filename in your file explorer, then copy-paste it directly into your code to avoid typos.

3. The file isn't where you think it is #

Sometimes files get moved accidentally, or you saved them to a different folder than intended.

• Manually navigate to the folder you expect the file to be in and confirm it's there.
• Use command line tools to verify: ls (Linux/macOS) or dir (Windows) to list the directory contents.

4. Rare: Permission issues (though error usually differs) #

If you’re sure the file exists but still get this error, double-check that your user account has access to the file or its parent folder. Note that this usually throws a PermissionError instead, but it’s worth ruling out if other fixes fail.

Work through these steps, and you’ll have your file reading code working consistently in no time.

内容的提问来源于stack exchange，提问作者Slumpe