PHP - 遇到的偏移错误[重复]

Not sure why I'm getting this error as the code is working and I can see the data I expected.

Code

$allSales = array();
foreach ($game['sales'] as $sale) {
  foreach ($sale['values'] as $id => $values) {
    $allSales[$id]+=$values['y'];
  }
}  

Error 1

A PHP Error was encountered

Severity: Notice

Message: Undefined offset: 0

Filename: player/game.php

Line Number: 81

Error 2 (Same Code)

A PHP Error was encountered

Severity: Notice

Message: Undefined offset: 1

Filename: player/game.php

Line Number: 81

</div>

The statement:

$allSales[$id] += $values['y'];

means to take the current value of $allSales[$id], add the value of $values['y'] to it, and store that result back in $allSales[$id]. But the first time that you encounter a particular $id, there is no $allSales[$id]. This results in the warning when you try to get its current value.

Change to:

if (isset($allSales[$id])) {
    $allSales[$id] += $values['y'];
} else {
    $allSales[$id] = $values['y'];
}

Or you could just prefix the line with @ to suppress warnings (I know purists will cry over this):

@$allSales[$id] += $values['y'];