dongxian4531
2015-05-25 15:28
浏览 27
已采纳

在php中意外输出ltrim

Can anybody explain this unusual output of ltrim

var_dump(ltrim('/btcapi/participation/set-user-event-participation','/btcapi'));

rticipation/set-user-event-participation //output

While expected output has

/participation/set-user-event-participation

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任何人都可以解释ltrim的这种不寻常的输出 

  var_dump（  ltrim（'/ btcapi / participation / set-user-event-participation'，'/ btcapi'））; 
 
rticipation / set-user-event-participation // output 
   \  n 
 
预期输出 
 
 <前>  / participation / set-user-event-participation
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3条回答 默认 最新

  • douren0558 2015-05-25 15:37
    已采纳

    Use str_replace if you are sure this is the only one occurence in your string.

    $str = '/btcapi/participation/set-user-event-participation';
echo str_replace('/btcapi', $str); // returns: '/participation/set-user-event-participation'

    Or regex if you need replace/remove just the first at the beginning of string.

    $str = '/btcapi/participation/set-user-event-participation';
preg_replace ('~^/btcapi~', '', $str);
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  • duandian8251 2015-05-25 15:30

    The trim characters are read as individuals, not as a String.

    It just replaces the second / for example because it is a part of the characters.

    Just use str_replace or a custom loop.

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  • duanrong0738 2015-05-25 15:32

    RTM: http://php.net/ltrim

    the second argument is a character MASK, e.g. characters you want to strip. CHARACTERS, not STRING.

    php > $foo = 'abc123';
php > echo ltrim($foo, 'abpq');
c123
php > echo ltrim($foo, 'a1');
bc123
  ^---not stripped, because 'bc' are not in the mask.
php >

    PHP will search strip all characters from the left of the string, based on the characters in the mask, until it encounters a character NOT in the mask.

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