使用preg_replace替换多次出现的相同符号？

Question

比方说，我有一个这样的字符串：

$string = "hello---world"; 

我将如何去用一个连字符替换---？ 字符串可以很容易地像这个：

$string = "hello--world----what-up"; 

期望的结果应该是：

$string = "hello-world-what-up"; 

Answer 1

$string = preg_replace('/-{2,}/','-',$string); 

Answer 2

尝试$string = preg_replace('/-+/', '-', $string)

Answer 3

$string = preg_replace('/--+/', '-', $string); 

Answer 4

下面是我使用的功能 - 作品像一个魅力:)

public static function setString($phrase, $length = null) { 
    $result = strtolower($phrase); 
    $result = trim(preg_replace("/[^0-9a-zA-Z-]/", "-", $result)); 
    $result = preg_replace("/--+/", "-", $result); 
    $result = !empty($length) ? substr($result, 0, $length) : $result; 
    // remove hyphen from the beginning (if exists) 
    $first_char = substr($result, 0, 1); 
    $result = $first_char == "-" ? substr($result, 1) : $result; 
    // remove hyphen from the end (if exists) 
    $last_char = substr($result, -1); 
    $result = $last_char == "-" ? substr($result, 0, -1) : $result;  
    return $result; 
} 

Answer 5

要从开头和结尾删除：

$string = trim($string, '-');