[PHP]unset構文と処理速度 ref: http://qiita.com/tarunama/items/3385acb60f20c055d048

これでも問題なく動く

<?PHP
$content = fopen($argv[1], "r");

while (($line = fgets($content)) !== false) {
    $ary = preg_split("/[\s]/", $line);
    $str = $ary[1];

    $pattern = preg_split("/[\\+\-]/", $ary[1]);

    foreach (str_split($pattern[0]) as $val) {
        $left[] = $val;
    }
    foreach (str_split($pattern[1]) as $val) {
        $right[] = $val;
    }
    $leftnumber     = substr($ary[0], 0, count($left));
    $rightnumber    = substr($ary[0], count($left));

    if (strstr($ary[1], "+")) {
        echo $leftnumber + $rightnumber . PHP_EOL;
    } elseif (strstr($ary[1], "-")) {
        echo $leftnumber - $rightnumber . PHP_EOL;
    }

    unset($left, $right);
}

fclose($content);

だけどこっちの方が処理は早い

<?PHP
$content = fopen($argv[1], "r");

while (($line = fgets($content)) !== false) {
    $ary = preg_split("/[\s]/", $line);
    $str = $ary[1];

    $pattern = preg_split("/[\\+\-]/", $ary[1]);

    foreach (str_split($pattern[0]) as $val) {
        $left[] = $val;
    }
    foreach (str_split($pattern[1]) as $val) {
        $right[] = $val;
    }
    $leftnumber     = substr($ary[0], 0, count($left));
    $rightnumber    = substr($ary[0], count($left));

    if (strstr($ary[1], "+")) {
        echo $leftnumber + $rightnumber . PHP_EOL;
    } elseif (strstr($ary[1], "-")) {
        echo $leftnumber - $rightnumber . PHP_EOL;
    }

    unset($left, $right, $rightnumber, $leftnumber);
}

fclose($content);