PHP idn_to_ascii() Function: Usage and Examples

Use idn_to_ascii() when you need to converts an internationalized domain name into an ASCII-compatible form in a PHP application. The examples below show the actual operation and its limitations.

What Is idn_to_ascii() in PHP?

Converts an internationalized domain name into an ASCII-compatible form. The exact signature supported by your installation depends on its PHP version and enabled extensions.

Its syntax is:

idn_to_ascii( /* parameters depend on the required extension and PHP version */ )

Availability: This function is not available in every PHP build. Install or enable the required extension or check the PHP version before using it.

Example 1: Basic Usage

<?php

if (function_exists("idn_to_ascii")) echo idn_to_ascii("bücher.example", IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46);

Result: Run the example in an environment that supports the function. Any values depending on operating-system state, installed extensions, process configuration, or network access must be checked on the target server.

Example 2: Different Input or Behavior

<?php

if (function_exists("idn_to_ascii")) var_dump(idn_to_ascii("example.com") === "example.com");

Result: Run the example in an environment that supports the function. Any values depending on operating-system state, installed extensions, process configuration, or network access must be checked on the target server.

Practical Example: Applying the Function

<?php

$domain = "bücher.example"; if (function_exists("idn_to_ascii")) { $converted = idn_to_ascii($domain,IDNA_DEFAULT,INTL_IDNA_VARIANT_UTS46); echo $converted === false ? "Invalid domain" : $converted; }

Result: Run the example in an environment that supports the function. Any values depending on operating-system state, installed extensions, process configuration, or network access must be checked on the target server.

Important Behavior and Edge Cases

Requires intl. IDN conversion is not URL validation or a phishing-defense mechanism.

Comparison With Related Functions

Common Beginner Mistakes

Key Takeaways

• Converts an internationalized domain name into an ASCII-compatible form.
• Requires intl. IDN conversion is not URL validation or a phishing-defense mechanism.
• idn_to_utf8() reverses ASCII-compatible IDN conversion.

Use idn_to_ascii() for the specific operation demonstrated above. Check its prerequisites and handle failure conditions before using it with production data.