百度谷歌搜索无果，只好自己造一次轮子。 php
/** * rpn2value * 计算逆波兰式 * @author leo108 root@leo108.com */function rpn2value($str){ $arr = explode(',',$str); $stack = array(); $len = count($arr); for($i=0;$i使用方法：
逆波兰式
$str = 1,2,3,+,*,4,-,5,+,7,*;echo rpn2value($str);
另附中序转后序代码，版权归原作者所有 http://leo108.com/pid-1901.asp
/** * math_rpn * * 实现逆波兰式算法 * * @author sparkhuang 260558820@qq.com * @version rpn 1.0.0 * */class math_rpn { //初始的计算表达式 private $_expression = ''; //处理后的逆波兰表达式 private $_rpnexp = array(); //模拟栈结构的数组 private $_stack = array('#'); //正则判断 //private $_reg = '/^([a-za-z0-9\(\)\+\-\*\/])*$/'; //优先级 private $_priority = array('#' => 0, '(' => 10, '+' => 20, '-' => 20, '*' => 30, '/' => 30); //四则运算 private $_operator = array('(', '+', '-', '*', '/', ')'); public function __construct($expression) { $this->_init($expression); } private function _init($expression) { $this->_expression = $expression; } public function exp2rpn() { $len = strlen($this->_expression); for($i = 0; $i _expression, $i, 1); if ($char == '(') { $this->_stack[] = $char; continue; } else if ( ! in_array($char, $this->_operator)) { $this->_rpnexp[] = $char; continue; } else if ($char == ')') { for($j = count($this->_stack); $j >= 0; $j--) { $tmp = array_pop($this->_stack); if ($tmp == () { break; } else { $this->_rpnexp[] = $tmp; } } continue; } else if ($this->_priority[$char] _priority[end($this->_stack)]) { $this->_rpnexp[] = array_pop($this->_stack); $this->_stack[] = $char; continue; } else { $this->_stack[] = $char; continue; } } for($i = count($this->_stack); $i >= 0; $i--) { if (end($this->_stack) == '#') break; $this->_rpnexp[] = array_pop($this->_stack); } return $this->_rpnexp; }}//测试实例$expression = (a*(b+c)-e+f)*g;var_dump($expression);$mathrpn = new math_rpn($expression);var_dump($mathrpn->exp2rpn());
中序表达式