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Comparison exceptions in PHP code

WBOY
Release： 2016-07-25 08:47:49
Original
958 people have browsed it
A big bug I encountered this morning is that when the student ID number on the school platform is an extremely long pure number, when comparing, it is found that they are all the same!
I wrote a simple one
and pasted it up, and I’d like experts to explain why!
I really didn’t notice this before~

This situation must be judged by ===. The judgment by == is always the same!
  1. $a = '440103001012201310030'; //Student ID 1
  2. $b = '440103001012201310032'; //Student ID 2
  3. if($a == $b)
  4. {
  5. echo '1---< br />';
  6. }
  7. else
  8. {
  9. echo '0---
    ';
  10. }
  12. $a = '2201310030'; //Comparison of short characters, student number 1
  13. $ b = '2201310032'; //Student number 2
  14. if($a == $b)
  15. {
  16. echo '2---
    ';
  17. }
  18. else
  19. {
  20. echo '0-- -
    ';
  21. }
Copy code
  1. 1---
  2. 0---
Copy code


Related labels：
PHP代码中比较异常
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