A detailed example of PHP 5.2.x array operation

Array manipulation in PHP 5.2.x

Just read the PHP Getting Started tutorial, summarize some of the PHP array operation caused by different PHP versions, some problems.

The following content is tested in the php5.2.5 environment.
1.

<?php$arr = Array ("a" = = 1, "b" = = 2, "c" = 3);

If this defines an array, it will report a compilation error:

Copy Code code example:

<?php$arr = Array ("A" = 1, "b" = 2, "c" = 3);

Therefore, when you define an array, you can only use the =

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<?php$arr = Array ("a" = = 1, "b" = 2, "c" = 3); echo $arr [0];echo $arr [1];

It was a blank shot.

The correct way to print:

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echo $arr ["a"];

3, add elements or modify the elements can only use =, can not use =

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<?php$arr = Array ("a" = = 1, "b" = 2, "c" = 3); $arr ["c"] = 6;

The above operation method, in PHP 5.2.5 will appear the compilation error

Add elements or modify elements to write this:

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<?php$arr = Array ("a" = = 1, "b" = 2, "c" = 3); $arr ["D"] = 4; $arr ["c"] = 6;

To delete an element, use unset:

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unset ($arr ["C"]);

4, think of the following code, what will output?

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<?php$arr = Array ("a" = =, "b" = 3,4); $arr [] = 5;foreach ($arr as $key + $value) {    echo "key: $key value: $value <br> ";}

Output Result:

Key:a value:1key:0 value:2key:b value:3key:1 value:4key:2 value:5

Note: PHP automatically uses a 0-based number as the key only if the user does not have a key defined.

5, the array in PHP is a pointer, you can forward and backward operation of the group

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<?php$arr = Array ("a" = = 1,3, "b" = 2);

After the array is created, the default pointer refers to the first element
Echo current ($arr). " <br> ";
Move forward a position
Echo Next ($arr). " <br> ";
The default rule for grooming is small to large
Sort ($arr);
After finishing the array pointer again stops at the first element
Echo current ($arr). " <br> ";
Echo Next ($arr). " <br> ";
Back one position
Echo prev ($arr). " <br> ";

Output Result:

13121