在PHP中的异常处理期间，预分配的变量已损坏

Question

The variable $maxTry is unassigned when an exception is raised and

the exception handling stops at nTry = 1.

How is this possible?

$nTry=0;
$maxTry=100;
function verify() { 
  try{
      // Some DB Connection
      $st = $dbh->prepare(...);
      $result = $st->fetchColumn();
  }
  catch(PDOException $e) {
    $nTry++;
    echo 'PDOException<br/>';
    if($e->getCode()==='HY000') {
        echo 'verify again<br/>';
        if($nTry < $maxTry) {
            $maxTry=100;
            verify();      //recursion
        }
        else 
            echo "Reached maxTry ($nTry __ $maxTry) PDOException: HY000<br/>";
    }
}
verify();

Expected output (if reached maxTry):

PDOException
verify again
...
verify again
Reached max try (100 __ 100) PDOException: HY000

Actual output ($maxTry is not set):

PDOException
verify again
Reached max try (1 __ ) PDOException: HY000

Answer 1

Since you are using the variables in a function, but declaring them outside, they are not accessible. You need to add this right after the the opening of the function.

function verify() { 
    global $maxTry, $nTry; // add this