Скачать или смотреть Understanding How to Save and Read Structures in C

Learn why only strings are saved when writing a structure to a file in C, and discover the best practices for saving integer and other variable data correctly.
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Understanding How to Save and Read Structures in C: A Guide for Beginners

When working with structures in C, developers often run into the challenge of saving data types correctly to a file. This guide will address a common issue related to writing integers and other data types from a structure to a text file in C, and we will provide you with a clear solution to help you successfully store your data.

The Problem: Data Types Not Writing to File

The Structure

The user shared a structure representing employee details, including variables of different types such as integers and strings:

[[See Video to Reveal this Text or Code Snippet]]

The function get_employee_details collects input from the user and stores it in the employee structure. However, when this structure is written to a file using fwrite, only string data seems to be saved. The user is confused as to why the integer data doesn't appear in the resulting file when opened with a text editor.

The Solution: Understanding fwrite and Alternative Methods

The problem lies in how fwrite works. Unlike strings, which are stored as human-readable characters, integers and other binary data types are stored as binary representations. Therefore, when you open the text file in a regular text editor, you won't see human-readable versions of your integer values; you will instead see non-readable characters. Here’s how you can tackle this problem effectively:

1. Use fwrite Correctly

The fwrite function can write your structure to a binary file successfully, but if you're looking to read the output with a text editor, it won't appear correctly. For binary data, the command you used is appropriate. If you later want to read it programmatically, you can use fread to retrieve the binary data.

2. Write Data in Human-Readable Format

If your goal is to write the data in a way that is readable in a text file, you should consider using fprintf instead of fwrite. Modify your add_employee function as follows to achieve this:

[[See Video to Reveal this Text or Code Snippet]]

This line will store the employee’s details in a format that's easy to read when opened in a text editor.

3. Implement Changes in Your Code

Here’s a revised version of your add_employee function incorporating the changes mentioned:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By using fprintf for writing to files, you ensure that your data is stored in a human-readable format, which makes it easier when you want to check what has been stored. This adjustment will resolve your issue of only seeing string data when checking the contents of your file. Remember, using fwrite is efficient for binary data manipulation, but for readable outputs, fprintf serves as the appropriate tool. Happy coding!