diff --git a/php/08_stack/Compute.php b/php/08_stack/Compute.php new file mode 100644 index 0000000..3e5624b --- /dev/null +++ b/php/08_stack/Compute.php @@ -0,0 +1,78 @@ += 48 && ord($arr[$i] <= 57)){ + array_push($numStack, $arr[$i]); + continue; + } + switch ($arr[$i]){ + case '+': + case '-': + $arrLen = count($operStack); + while ($operStack[$arrLen-1] === '*' || $operStack[$arrLen-1] === '/' || $operStack[$arrLen-1] === '-'){ + compute($numStack, $operStack); + $arrLen--; + } + array_push($operStack, $arr[$i]); + break; + case '*': + case '/': + case '(': + array_push($operStack, $arr[$i]); + break; + case ')': + $arrLen = count($operStack); + while ($operStack[$arrLen-1] !== '('){ + compute($numStack, $operStack); + $arrLen--; + } + array_pop($operStack); + break; + default: + throw new \Exception("不支持的运算符", 1); + break; + } + } + + $arrLen = count($operStack); + while ($operStack[$arrLen-1] !== NULL){ + compute($numStack, $operStack); + $arrLen--; + } + echo array_pop($numStack); +} + +//数字栈长度减一,运算符栈长度减一 +function compute(&$numStack, &$operStack){ + $num = array_pop($numStack); + switch (array_pop($operStack)) { + case '*': + array_push($numStack, array_pop($numStack) * $num); + break; + case '/': + array_push($numStack, array_pop($numStack) / $num); + break; + case '+': + array_push($numStack, array_pop($numStack) + $num); + break; + case '-': + array_push($numStack, array_pop($numStack) - $num); + break; + + } +} +expression('-1+2-(1+2*3)'); +echo PHP_EOL; +eval('echo -1+2-(1+2*3);'); \ No newline at end of file