Detailed explanation of simple and fast PHP array assignment method

Detailed explanation of simple and fast PHP array assignment method_PHP tutorial

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Release： 2016-07-15 13:27:25

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PHP arrays are quite commonly used, so I studied PHP array assignment and shared it with you here. I hope it will be useful to everyone. The so-called array is a collection of variables stored in the computer's memory. These variables can be of different types, including integers, Boolean values, strings, etc. It can be said that an array is a small database in memory. It provides a quick way for us to access data - it can save IO or frequent database access to improve some performance, so there are many operations on the array.

How to create an array in PHP You can create an array using one of the following methods:

<ol class="dp-xml"><li class="alt">
<span><strong><font color="#006699"><span class="tag"><?</SPAN><SPAN class=tag-name>php</SPAN></FONT></STRONG><SPAN> </SPAN></SPAN><LI class=""><SPAN>$</SPAN><SPAN class=attribute><FONT color=#ff0000>a</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>"abcd"</FONT></SPAN><SPAN>;  </SPAN></SPAN><LI class=alt><SPAN>print($a[0]." ".$a[1]." ".$a[2]." ".$a[3]." ");  </SPAN><LI class=""><SPAN></SPAN><SPAN class=tag><STRONG><FONT color=#006699>?></span></font></strong></span><span> </span>
</li></ol>

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Result: a b c d

Method 2:

<ol class="dp-xml"><li class="alt">
<span><strong><font color="#006699"><span class="tag"><?</SPAN><SPAN class=tag-name>php</SPAN></FONT></STRONG><SPAN> </SPAN></SPAN><LI class=""><SPAN>    </SPAN><LI class=alt><SPAN>$</SPAN><SPAN class=attribute><FONT color=#ff0000>http</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>array</FONT></SPAN><SPAN>("www","helpphp","cn");  </SPAN></SPAN><LI class=""><SPAN>    </SPAN><LI class=alt><SPAN>print($http[0].".".$http[1].".".$http[2]);  </SPAN><LI class=""><SPAN>    </SPAN><LI class=alt><SPAN></SPAN><SPAN class=tag><STRONG><FONT color=#006699>?></span></font></strong></span><span> </span>
</li></ol>

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Knowledge Note: 1. We can see from the previous example that arrays in PHP start from the subscript (index) by default to indicate the position of the variable in the array, also That is to say, we can use the form: $variable name [index] to access the array we created. 2. We use the array() language structure to create data. In the array, if the subscript is not explicitly specified, the index starts from 0 and increases by default. The array we created has been saved in memory, but after the data is used, we need to do some cleaning. To ensure memory leaks, I believe this will be covered in future chapters. Explain the assignment and destruction of PHP arrays. If you haven’t learned: PHP arrays, you should learn about them first.

How to assign values to PHP arrays? As follows:

<ol class="dp-xml">
<li class="alt"><span><span>$</span><span class="attribute"><font color="#ff0000">My_array</font></span><span>=array()；  </span></span></li>
<li class=""><span> </span></li>
<li class="alt"><span>$My_array[]=”www”  </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>$My_array[]=”helpphp”;  </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>$My_array[]=”cn”;  </span></li>
</ol>

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Through the above method, I created an empty array for the variable using the array language structure, and assigned a value to $My_array in the following statement. In the previous section, we know that, The array subscript (index) automatically increases from 0, which means that the following statement will output helpphp.

<ol class="dp-xml"><li class="alt"><span><span>Print $My_array[1]; </span></span></li></ol>

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If you want to output $My_array all at once, you can use print_r($My_array). How to destroy the array Or if the elements in the array want to complete the above tasks, just use the unset() function, which can delete the entire array or an element in the array, as follows:

<ol class="dp-xml">
<li class="alt"><span><span>unset($My_array[0];  </span></span></li>
<li class=""><span> </span></li>
<li class="alt"><span>unset($My_array);  </span></li>
</ol>

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It should be noted that, in After deleting an array element, the index value will retain its original position and the index will not be readjusted. You only need to compare after deletion to find this phenomenon. Use var_dump() to view more detailed things in the array, as follows:

<ol class="dp-xml"><li class="alt"><span><span>Var_dump($My_array);  </span></span></li></ol>

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