substr not working | 仅显示数组的第一个值的输出

Question

I want to use just the filename from each file for my further coding. How can i do that. I used substr but it is working just on the first line. Array $S2 holds:

access.2018.08.09.log|201808101105
access.2018.08.12.log|201808101105
access.2018.08.13.log|201808101105

I want just the text before '|' :-

access.2018.08.09.log
access.2018.08.12.log
access.2018.08.13.log

Code:-

<pre><?php

$files = scandir('C:\wamp64\www\MyLogs\logsfiles');
foreach($files as $key => $file) {
    if($file == '.' || $file == '..') unset($files[$key]);
}

$S2 = explode("
", substr(file_get_contents('uplodedregistry.txt'),0,21));

$result = array_diff($files, $S2);
print_r($result);

?>

Answer 1

The problem is the order you are doing this

$S2 = explode("
", substr(file_get_contents('uplodedregistry.txt'),0,21));

You need to explode the lines, loop through them then do the sub-string if you want all the entries.

AS it stands you just grab the first one, then attempt to explode it on line endings which it doesn't have.

If we step through what your code does.

1 - get contents (added ', and for readability)

'access.2018.08.09.log|201808101105

access.2018.08.12.log|201808101105

access.2018.08.13.log|201808101105
'

2 - sub string 0 to 21 of the above string

'access.2018.08.09.log'

3 - explode with the above string

['access.2018.08.09.log']

Instead do something like this:

  $content = explode("
", file_get_contents('uplodedregistry.txt'));

  foreach($content AS &$row){
       $row = substr($row,0,21);
  }

Note - updated by reference using the &. This way we don't have to make a new array.

In contrast to the above this is what this does:

1 - (Same as above)

'access.2018.08.09.log|201808101105

access.2018.08.12.log|201808101105

access.2018.08.13.log|201808101105
'

2 - explode above string on

array(
  'access.2018.08.09.log|201808101105',
  'access.2018.08.12.log|201808101105',
  'access.2018.08.13.log|201808101105'
)

3 - Foreach element (loop through above array)

//iteration 1.  substr('access.2018.08.09.log|201808101105',0,21);
//iteration 2.  substr('access.2018.08.12.log|201808101105',0,21);
//iteration 3.  substr('access.2018.08.13.log|201808101105',0,21);

Then because its update by reference if you do print_r($content) You should have this array

 array(
    'access.2018.08.09.log',
    'access.2018.08.12.log',
    'access.2018.08.13.log'
)

Also you can remove this loop

$files = scandir('C:\wamp64\www\MyLogs\logsfiles');
foreach($files as $key => $file) {
   if($file == '.' || $file == '..') unset($files[$key]);
}

By using

$files = array_diff(scandir('C:\wamp64\www\MyLogs\logsfiles'), ['.','..']);

Array diff returns the entries from Array1 that are not present in any of the argument arrays. So in this case it will return everything but . and ... The nice thing about this method is it's easy to add more files to the list, if there is other files you wish to exclude. It's also a lot cleaner and takes only 1 line.

Lastly I should mention there are other methods you could use to do this, for example

   preg_match_all('/^([^|]+)/', file_get_contents('uplodedregistry.txt'), $matches);

Or probably the best way is to use CSV reading, but use the pipe | instead of , as the delimiter.

$f = fopen('uplodedregistry.txt', 'r');
$contents = [];
while (FALSE !== ($row = fgetcsv($f, 1000, "|"))){
      $contents[] = $row[0];
}

I would really consider using CSV

fgetcsv ( resource $handle, int $length = 0, string $delimiter = ",", string $enclosure = '"' , string $escape = "\")

http://php.net/manual/en/function.fgetcsv.php

I mention these because sometimes you can have issues exploding on line endings depending on what OS creates the file:

     // 
 - linux
     // 
 - win
     //  - older Mac OS

Cheers.