How to solve the problem of inverse Polish expression calculation

Reverse Polish expression computing recently found some interesting code programs from previous collections that are gradually ported to PHP for interested people to refer to PHPcode/*** reverse Polish expression calculation * infix to suffix **/functionpostfix ($ infix) {$ priority = array (// operator inverse Polish expression calculation
I recently found some interesting code from my previous favorites during data sorting.
Plan to gradually port them to PHP for reference

PHP code

  /***** Inverse Polish expression calculation * infix to suffix **/function postfix ($ infix) {$ priority = array (// operator priority '+' => 1, '-' => 1, '*' => 2, '/' => 2, '(' => 0, ')' => 0 ,'. '=> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); $ stack = array (); // symbol stack $ data = array (); // value stack $ I = $ top = 0; $ last =-1; $ len = strlen ($ infix ); while ($ I <$ len) {switch ($ infix {$ I}) {case '(': array_unshift ($ stack, $ infix {$ I}); break; case '+': case '-': case '*': c Ase '/': if ($ t! = '') Array_unshift ($ data, $ t); $ t = ''; while ($ priority [$ stack [0]> = $ priority [$ infix {$ I}]) {postfix_callback (array_shift ($ stack), $ data );} array_unshift ($ stack, $ infix {$ I}); break; case ')': if ($ t! = '') Array_unshift ($ data, $ t); $ t =''; while ($ stack [0]! = '(') {Postfix_callback (array_shift ($ stack), $ data);} array_shift ($ stack); break; default: if ($ I> $ last + 1 & $ t! = '') {Array_unshift ($ data, $ t); $ t ='';} $ t. = $ infix {$ I}; $ last = $ I; break;} $ I ++;} while ($ stack) {postfix_callback (array_shift ($ stack ), $ data);} return $ data [0];}/*** postfix function * used to calculate the expression value **/function postfix_callback ($ ch, & $ data) {$ B = array_shift ($ data); switch ($ ch) {case '+': $ data [0] + = $ B; break; case '-': $ data [0]-= $ B; break; case '*': $ data [0] * = $ B; break; case '/': $ data [0]/= $ B; break ;}}

Test example

PHP code

  echo postfix( '(2+3)*(3+4)' ); //out 35

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Paste it back first
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This is a good thing.

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The front row occupies the seat, and the boss is awesome.
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The front row occupies the seat, and the boss is awesome.