PHP in a "pit", php "pit" _php tutorial

A "pit" in PHP, PHP "pit"

To say a very likely problem encountered at work--foreach reference

$arr Range (1,3); // [A] foreach ($arr as &$val) {} foreach ($arras$val) {} Print_r ($arr

Above this code output what, magical unexpectedly is the following, this I met once in the work, at that time did not make a day, but found a solution, this problem solution has two:

Array (    [0] = 1    [1] = 2    [2] = 2)

Both of the following methods can solve the problem above:

 //  Method 1   foreach  ( $arr   as  &  $value  ) {}   unset  ( $value  );   foreach  ( $arr   as   $value  ) {}   Print_r  ( $arr  );  //  [1,2,3]//Method 2   foreach  ( $arr   as  &  $value  ) {}   foreach  ( $arr   as   $val  ) {}   Print_r  ( $arr  );  //  [1,2,3]//Method 3   foreach  ( $arr   as  &  $value  ) {}   foreach  ( $arr   as  &  $value  ) {}   Print_r  ( $arr  );  //  [I/a]  

Method 1 in the official manual can also see http://php.net/manual/en/control-structures.foreach.php, the article has a tips tip this $var = 123; $tmp = &$var; $tmp = $; Echo $var ; // $

Look at this stolen picture below (haha, the original link is posted below), on the above this better understanding

PHP$arr 1 = array("a" = 1, "b" = 2, "c" = 3); $arr 2 = array("x" = 4, "Y" = 5, "z" = 6); foreach ($arr 1 as $key = &$val) {} foreach ($arr 2 as $key = + $val) {} Var_dump ($arr 1); Var_dump ($arr 2);? > Theoutputis:array(3) {["a"]=> int (1) ["B"]=> int (2) ["C"]=> &int (6)} Array(3) {["X"]=> int (4) ["Y"]=> Int (5) ["Z"]=> int (6)}

Reference article:

http://www.cnblogs.com/CraryPrimitiveMan/p/4030748.html#3085766

Http://www.jb51.net/article/39299.htm

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