Convert All Types of Smart Quotes in PHP

Smart quotes are typographic marks used in place of regular straight quotes (' and "). They give a more refined and polished look to text. However, it's common for software applications to struggle with converting between different types of smart quotes, leading to inconsistencies.

Challenges in Smart Quote Conversion

The difficulty in converting smart quotes arises from the variety of encodings and characters used to represent them. Different operating systems and software programs employ their own standards, resulting in a fragmented landscape of quote characters. For instance, one system may use Unicode, while another may use Windows codepage 1252.

Comprehensive Conversion with PHP

To address this challenge, a comprehensive smart quote conversion function in PHP requires a thorough understanding of the different encodings and characters involved. It should be able to handle all variations of smart quotes, including those defined in Unicode, Windows codepage 1252, and other legacy encodings.

Optimized PHP Implementation

The following optimized PHP implementation converts all types of smart quotes to regular quotes:

function convert_smart_quotes($string)
{
    // Create a map of smart quote characters to their respective Unicode representations
    $smart_quotes = array(
        "\xC2\xAB" => '"', // « (U 00AB)
        "\xC2\xBB" => '"', // » (U 00BB)
        "\xE2\x80\x98" => "'", // ‘ (U 2018)
        "\xE2\x80\x99" => "'", // ’ (U 2019)
        "\xE2\x80\x9A" => "'", // ‚ (U 201A)
        "\xE2\x80\x9B" => "'", // ‛ (U 201B)
        "\xE2\x80\x9C" => '"', // “ (U 201C)
        "\xE2\x80\x9D" => '"', // ” (U 201D)
        "\xE2\x80\x9E" => '"', // „ (U 201E)
        "\xE2\x80\x9F" => '"', // ‟ (U 201F)
        "\xE2\x80\xB9" => "'", // ‹ (U 2039)
        "\xE2\x80\xBA" => "'", // › (U 203A)
    );

    // Strtr function can directly replace the smart quote characters with their Unicode counterparts
    $converted_string = strtr($string, $smart_quotes);

    // Return the converted string
    return $converted_string;
}

This function covers a wide range of smart quote variations, including those found in Unicode, Windows codepage 1252, and legacy encodings. By using strtr, it replaces all instances of smart quotes with their corresponding Unicode representations, resulting in a consistent and standardized text.