Displaying the Delete (DEL) Control Character in JSON Encoded Strings

Discover how to reveal the hidden `127` ASCII character in JSON strings, and learn about encoding in PHP.
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Displaying the Delete (DEL) Control Character in JSON Encoded Strings

When dealing with JSON data in PHP, especially when encoding strings, you may encounter various ASCII characters. One such character is the Delete (DEL) character, which corresponds to the ASCII code 127 (or 0x7f in hexadecimal). The problem arises when you notice that this character is not embedded in the JSON string when outputting it. Instead, you're left with a representation of all other characters, leaving you to wonder how to include or display this elusive ASCII 127 character. Let’s dive deep into this issue and explore a solution.

Understanding the Problem

Consider the following PHP code snippet designed to generate a string consisting of ASCII characters through the json_encode function.

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

This code produces JSON output that includes all of the ASCII characters except for 127 (0x7f), which, as a control character, is omitted. If you run the above code, you'll see the JSON string showcasing characters from 0 to 126, but where's the Delete character?

The Deleted Character

The Delete (DEL) character is a control character in the ASCII set that often causes confusion during string manipulations and displays, particularly in web browsers. When outputting this character in JSON, it is typically represented as an empty space or not shown at all. To bring this character back into focus, we need to use a different approach to reveal it.

How to Show the DEL Character

Step 1: Encoding the DEL Character

To make the Delete character visible, we can handle its encoding in a specific way. The key here is to convert this character into a hexadecimal format using PHP’s bin2hex function, which converts binary data into a hexadecimal representation. You can follow this example:

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

Explanation:

chr(0x7f): This function call produces the Delete character.

json_encode(...): We are encoding it to format it into JSON.

bin2hex(...): This will provide a hexadecimal representation of the JSON-formatted string.

Step 2: Understanding the Output

The output of the above code snippet will yield 227f22, where:

22 represents the encoding for a double quotation mark ".

7f is the actual encoding for the Delete character.

This output provides a clear visibility into the character without graphical representation.

Final Notes

It’s important to remember that PHP string functions can often lead to misunderstandings when dealing with control characters such as the DEL. In web visuals, these characters might not show up, appearing as spaces instead. This nuance can be crucial when debugging JSON outputs or ensuring that data is preserved correctly.

To summarize, if you're working with JSON and need to represent or verify the presence of the Delete character, use bin2hex on the result of json_encode applied to chr(0x7f). This way, you will see the representation instead of an empty space in your outputs.

By understanding how to work with character encodings, you can have better control over how your data is stored and represented, ensuring that nothing is unintentionally omitted.