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  1. <?php
  2. $input='243 + 6743 - 78 * 2 =';
  3. echo "At first I was like $input...\n";
  4. preg_match('/^[1-9]*/',$input,$match);
  5. $sum=$match[0];
  6. $operand1=$match[0];
  7. $substrLength=strspn($input,"1234567890",(strlen($sum)+1));
  8. calculateIt($input,$operand1,(substr($input,strlen($sum)+1,$substrLength)),$sum);
  9.  
  10. function calculateIt($input,$operand1,$operand2,$sum)
  11. {
  12.  
  13. $substrLength=strspn($input,"1234567890",(strlen($sum)+1));
  14. $operand2=substr($input,strlen($sum)+1,$substrLength);
  15. $oper=substr($input,(strlen($sum)),1);
  16. switch ($oper)
  17. {
  18.     case "+": $sum+=$operand2; break;
  19.     case "-": $sum-=$operand2; break;
  20.     case "*": $sum*=$operand2; break;
  21.     case "/": $sum/=$operand2; break;
  22. }
  23. $input=str_replace($operand1.$oper.$operand2,$sum,$input);
  24. echo "...and then I    $input \n";
  25. $operand1=$sum;
  26. if (substr($input,strlen($sum),1)!='=')
  27. calculateIt($input,$operand1,$operand2,$sum);
  28. else echo "Finally I became this... $sum";
  29. }
Success #stdin #stdout 0.01s 20520KB
comments (?)
stdin 
Standard input is empty
stdout 
At first I was like 243 + 6743 - 78 * 2 =...
...and then I    243+ 6743 - 78 * 2 = 
...and then I    243 6743 - 78 * 2 = 
...and then I    243 - 78 * 2 = 
...and then I    243- 78 * 2 = 
...and then I    243 78 * 2 = 
...and then I    243 * 2 = 
...and then I    243* 2 = 
...and then I    0 2 = 
...and then I    0 = 
...and then I    0= 
Finally I became this... 0
https://ideone.com/qJC97Y
language:
PHP (php 7.3.5)
created:
10 years ago
visibility:
secret

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