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PHP 5.2.x array operation details sharing

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Release： 2016-07-25 08:55:41
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  2. $arr = array("a" => 1,"b" => 2,"c" => 3);
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If Defining an array like this will result in a compilation error:

  3. $arr = array("a" = 1,"b" = 2,"c" = 3);
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Therefore, when defining the array Can only be used => 2,

  2. $arr = array("a" => 1,"b" => 2,"c" => 3);
  3. echo $arr[0];
  4. echo $arr[1];
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The result will be blank.

Correct printing method:

  2. echo $arr["a"];
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3. When adding elements or modifying elements, you can only use =, not =>

  2. $arr = array("a" => 1,"b" => 2,"c" => 3);
  3. $arr["c"] = > 6;
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The above operation method will cause a compilation error in php 5.2.5

To add elements or modify elements, write like this:

  2. $arr = array("a" => 1,"b" => 2,"c" => 3);
  3. $arr["d"] = 4;
  4. $arr["c"] = 6;
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To delete elements, use unset:

  2. unset ($arr["c"]);
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4. Think about the following code, what will be output?

  2. $arr = array("a" => 1,2,"b" => 3,4);
  3. $arr[] = 5;
  4. foreach($arr as $key => $value)
  5. {
  6. echo "key:$key value:$value
    ";
  7. }
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Output result:

  2. $arr = array("a" => 1,3,"b" => 2);
  3. //After creating the array, the default pointer points to the first element
  4. echo current($arr)."
    ";
  5. //Go forward one position
  6. echo next($arr)."
    ";
  7. //The default principle of sorting is from small to large
  8. sort( $arr);
  9. //After finishing, the array pointer stops at the first element
  10. echo current($arr)."
    ";
  11. echo next($arr)."
    ";
  12. //Go back one position
  13. echo prev($arr)."
    ";
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Output result: 1 3 1 2 1



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php 5.2.x 数组操作细节分享
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