Hướng dẫn write a php script to get the last three characters of a string. - viết một tập lệnh php để lấy ba ký tự cuối cùng của một chuỗi.

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function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

com

function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

com

function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

com

/** Unlike substr, handles case where $string is too short.
 * @param $string
 * @param $nChars - negative to return at end of string.
 */
function safe_substr($string, $nChars) {
    if ($nChars == 0 || !isset($string))
        return "";

    if (strlen($string) <= abs($nChars))
        // $string is too short (or exactly the desired length). Return the string.
        return $string;

    return substr($string, $nChars);
}

Input : $str = "GeeksforGeeks!"
        $n = 6 
Output : Geeks!

Input : $str = "GeeksforGeeks!"
        $n = 9
Output : forGeeks!

function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

Example:

$str = "GeeksforGeeks!"

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function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

com

com

function str_replace_first($from, $to, $content)
{
    $from = '/'.preg_quote($from, '/').'/';

    return preg_replace($from, $to, $content, 1);
}

echo str_replace_first('abc', '123', 'abcdef abcdef abcdef'); 
// outputs '123def abcdef abcdef'

com

/** Unlike substr, handles case where $string is too short.
 * @param $string
 * @param $nChars - negative to return at end of string.
 */
function safe_substr($string, $nChars) {
    if ($nChars == 0 || !isset($string))
        return "";

    if (strlen($string) <= abs($nChars))
        // $string is too short (or exactly the desired length). Return the string.
        return $string;

    return substr($string, $nChars);
}