IntlChar charDirection() function in PHP

The IntlChar charDirection() function is used to determine the bidirectional category value for a given character, which is essential for proper text rendering in multilingual applications.

Syntax

int IntlChar::charDirection(mixed $codepoint)

Parameters

• $codepoint − An integer codepoint value or a character encoded as a UTF-8 string.

Return Value

The function returns an integer representing the bidirectional category. Common return values include ?

• IntlChar::CHAR_DIRECTION_LEFT_TO_RIGHT (0) − Left-to-right characters like Latin letters

• IntlChar::CHAR_DIRECTION_RIGHT_TO_LEFT (1) − Right-to-left characters like Arabic letters

• IntlChar::CHAR_DIRECTION_EUROPEAN_NUMBER (2) − European digits (0-9)

• IntlChar::CHAR_DIRECTION_EUROPEAN_NUMBER_SEPARATOR (3) − Separators like plus/minus signs

• IntlChar::CHAR_DIRECTION_OTHER_NEUTRAL (10) − Other neutral characters

• And 18 other directional constants for various Unicode categories

Example

Here's how to check the directional properties of different characters ?

<?php
echo "Character direction analysis:<br>";

// Latin letter (Left-to-right)
echo "Letter 'A': " . IntlChar::charDirection("A") . "<br>";

// European number separator
echo "Plus sign '+': " . IntlChar::charDirection("+") . "<br>";

// Dash/minus sign
echo "Dash '-': " . IntlChar::charDirection("-") . "<br>";

// Other neutral character
echo "Asterisk '*': " . IntlChar::charDirection("*") . "<br>";

// Invalid multi-character string returns NULL
echo "Multi-char 'abc': ";
var_dump(IntlChar::charDirection("abc"));

// Using Unicode codepoint directly
echo "Unicode U+0041 (A): " . IntlChar::charDirection(0x0041) . "<br>";
?>

Character direction analysis:
Letter 'A': 0
Plus sign '+': 3
Dash '-': 3
Asterisk '*': 10
Multi-char 'abc': NULL
Unicode U+0041 (A): 0

Key Points

• Returns NULL for invalid input or multi-character strings

• Accepts both character strings and Unicode codepoint integers

• Essential for implementing bidirectional text algorithms

• Different character types return different directional category values

Conclusion

The IntlChar::charDirection() function is vital for internationalization, helping determine how characters should be rendered in mixed-direction text layouts. It returns specific integer constants representing Unicode bidirectional categories.