使用字符串时，在in_array（）上警告第二个参数的数据类型错误

Question

Im using this code to read out of a file, Im getting an error Warning on in_array() for Wrong datatype for second argument.

if (isset($_POST['submit'])) {
  $SongToAdd = stripslashes($_POST['SongName']) . "\n";
  $ExistingSongs = array();

  if (file_exists("SongOrganizer/songs.txt") && filesize("SongOrganizer/songs.txt") > 0) {
    $ExistingSongs = file("SongOrganizer/songs.txt");
  }
}

if (in_array($SongToAdd, $ExistingSongs)) {
  echo "<p>The song you entered already exists!<br />\n";
  echo "Your song was not added to the list.</p>";

The text file contains:

Bang Bang
Doctor
Hello
Ice Cream Man
Show Me
Doctor

Answer 1

Well, what about the first time your page loads? If $_POST['submit'] is not set then $ExistingSongs will be null . in_array is right to complain about that.

If you were developing with all errors enabled -- done with error_reporting(E_ALL | E_STRICT) or through php.ini -- then you 'd also have gotten a notice about $ExistingSongs being an undefined variable.

Answer 2

如果未设置$_POST['submit']变量，则$ExistingSongs变量将保持未定义状态，这可能会引起警告。

Answer 3

stripslashes expects a string as input, and outputs a string: http://php.net/stripslashes

$SongToAdd is a string when you call in_array() , hence your error.