Analytic algorithm of calculation

These days nothing is written in PHP with a parser program.

For example: (21*12-23-(21+14-(21-31/3+ (14-21*12-14)) +54)-21) +21*25-22*26

Then the result of the analysis is:-169.33.

The code is now posted, if there is a bad place also ask the programmer friends to point out.

if (Isset ($_get[' Sizhi ')) {$sizhi =$_get[' Sizhi '];    if (!checksizhi ($sizhi)) {echo (' The formula is not valid, check if the parentheses are paired ');     }else{$sizhi =priority ($sizhi);     Echo (Calculate ($sizhi));    }}//Check whether the calculation is legal function Checksizhi ($sizhi) {$Amatch =array (); $pattern = '/((\d|!) \()| ([-\+\*\/]\))|    [^-\+\*\/!\d\ (\)]/';      if (Preg_match ($pattern, $sizhi, $Amatch) >0) {echo (' illegal element: ');      Print_r ($Amatch);    return false;      }else{$kuohao = 0;         For ($i =0, $k =strlen ($sizhi), $i < $k, $i + +) {if ($sizhi [$i]== "(") {$kuohao + +);               } if ($sizhi [$i]== ")") {$kuohao-;         if ($kuohao <0) return false;      }} if ($kuohao!=0) return false;    return true; }}//gets the priority to handle the contents of the parentheses in the function priorities ($sizhi, $start =0) {for ($i = $start; $i
 
  0) {echo ("factorial phase problem, please change the formula");  Exit ();    }else{//Replaces part of all factorial $sizhi =preg_replace_callback ($par, function ($siz) {return calculatefactorial ($siz [0]);  }, $sizhi); //Exchange symbols and numbers and calculate return change ($sizhi);} Calculates the factorial function calculatefactorial ($sizhi) {for ($i =0; $i
  
   0) {$str = $array [0];    } return $STR; }}
  
 

The above describes the calculation of the analytic algorithm, including the aspects of the content, I hope that the PHP tutorial interested in a friend helpful.

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