Creating a Directory Listing Application in C: Using dirent and stat Functions

Описание: Learn how to build a directory listing application in C, similar to the `ls` command, by utilizing `dirent` and `stat` functions effectively.
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This video is based on the question https://stackoverflow.com/q/71526424/ asked by the user 'bizariuz' ( https://stackoverflow.com/u/15614523/ ) and on the answer https://stackoverflow.com/a/71527166/ provided by the user 'Alex Nicolaou' ( https://stackoverflow.com/u/18349185/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Building a Directory Listing Application in C

Creating a directory listing application can be quite fulfilling, especially if you're familiar with the command-line tools like ls on Linux. If you're aiming to build a similar tool in C, leveraging the dirent and stat libraries is key to getting the relevant information about files in a directory. In this guide, we'll walk through how to effectively list files while retrieving their sizes—both the actual size and the size as stored on disk.

Understanding the Problem

You want to create a function in C that lists all files in a specified directory. This function should provide comprehensive details about each file, similar to how ls works. Specifically, you wish to display:

The size of each file

The size of each file on disk

The name of each file

In this endeavor, you're trying to utilize the stat function for file size information and the dirent structure to retrieve file names. However, it seems there was a critical oversight—the stat function wasn't called on the file names extracted using readdir. Let's explore how to correct this and improve your function.

Implementation Steps

1. Include Necessary Libraries

First, ensure you include the proper headers at the beginning of your code to access the functions required for directory operations and file stats.

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2. Define a Print Function

As per your provided code, you will want to maintain the existing _printLine function, which formats and prints file details.

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3. Open the Directory

Using opendir, you can access the specified directory. Ensure to handle any potential errors.

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4. Loop Through Directory Entries

Use readdir to loop through all directory entries. Within this loop, call stat for each file to get its size metrics.

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5. Close the Directory

Always remember to close the directory once your operations are complete.

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6. Main Function

Your main function should call the listing function and pass the directory path as an argument.

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Example of the Full Code

Here’s what the complete code would look like:

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Conclusion

By effectively utilizing the dirent and stat functions, you can successfully create a directory listing tool that provides useful file information. Be sure to include error handling in your implementation to capture issues with file access or reading directory contents.

Remember:

Check for errors when dealing with file operations.

Use stat correctly to gather necessary file information before attempting to print it.

Embark on your journey to enhance this basic application further by adding features like sorting or filtering based on file types! Happy coding!