如何检查txt文件中是否已存在值

问题描述：

I am writing UserID's to a text file seperated with || The var $UserID is an integer like 1, 2, 3 etc.

If a user has ID 1; the value is stored in the txt file and looks after some time like this:

1||1||1||1||1||...

What i want to achieve: if an ID is already stored in the txt file, do not store it again.

this is what i have sofar;

$UserIdtxt = $UserID."||";


$ID = explode("||", file_get_contents("user_id.txt"));
  foreach($ID as $IDS) {

// here must come the check if the ID already is stored in the txt file
     if($IDS != $UserID) {
     file_put_contents("user_id.txt", $UserIdtxt, FILE_APPEND);

     }
  }

How can i make that check?

我正在将UserID写入一个用|| code>分隔的文本文件 var $ UserID code>是一个整数，如1,2,3等。 p>

如果用户的ID为1; 该值存储在txt文件中，并在一段时间后查看： p>


  1 || 1 || 1 || 1 || 1 || ...   code>  p> 
 
 
我想要实现的目标：
如果ID已经存储在txt文件中，请不要再存储它。 p> 
 
 

 this 是我的软件;  p> 
 
 
  $ UserIdtxt = $ UserID。“||”; 
 
 
 $ ID = explode（“||”，file_get_contents（“  user_id.txt“））; 
 foreach（$ ID as $ IDS）{
 
 //这里必须检查ID是否已存储在txt文件中
 if（$ IDS！= $ UserID）  {
 file_put_contents（“user_id.txt”，$ UserIdtxt，FILE_APPEND）; 
 
} 
} 
  code>  pre> 
 
 如何进行检查？ 
  div>

答

All you need to do is test if the new ID is aleady in the exploded array using in_array()

$UserIdtxt = $UserID."||";

$all_ids = explode("||", file_get_contents("user_id.txt"));

if ( ! in_array($UserID, $all_ids) ) {
    file_put_contents("user_id.txt", $UserIdtxt, FILE_APPEND);
}

But this is an awful way of storing this kind of information

答

Prob a good idea to make sure the file was read successfully before you scan it

if($source = file_get_contents("user_id.txt"){
    if(!preg_match("/^($UserID|.*\|\|$UserID)/", $source){
        ... //add id to file
    }
}else{/*Todo: handle file-open failure*/}

如何检查txt文件中是否已存在值

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