Comprehensive study of PHP array initialization principles_PHP tutorial

PHP has powerful functions, and more and more people are using it. Here we will give you a detailed introduction to PHP array initialization. From the first introduction to ASP to PHP, I feel that one of the strengths of PHP is the richness of built-in functions. For example, the PHP date and time functions I learned earlier, the related functions for reading and writing files, etc. all show that PHP is more professional and easier for users to use. Handy.

At first I was very excited about the rich functions of PHP functions. As I came into contact with more and more almost abnormal functions, I suddenly thought of the scarcity of ASP built-in functions. To complete a certain special function, it is often necessary to It is necessary to customize functions. As the number of applications increases, I actually have a set of commonly used function libraries. However, now in PHP, these functions have long been standardized, normalized and condensed into built-in functions for direct use. Former ASP developers have become ordinary users of PHP.

But on second thought, the existence of these functions and these large numbers of PHP functions at least shows that PHP is more professional; at the same time, it should be very fast and easy to use when processing our daily PHP programs, which makes development People no longer customize functions for basic and detailed functions, but focus on building more powerful program modules. Therefore, I have strengthened my belief in taking a look at PHP functions, but I think that in the future development process, the PHP function manual should be a portable book.

Of course, there is no need to discuss the debate about the advantages and disadvantages of ASP and PHP. Learning and understanding can help you understand the truth. To be honest, there are too many functions in PHP to prevent forgetting, so every time I read a type of function, I make a summary and collection work, and write a log for convenience.

PHP array initialization and definition

What is an array? An array is a programming structure that is a variable that stores a set or series of values. For example, the identity registration of individuals during the census, such as name, gender, ethnicity, birth, etc., can be used as an array. Creating an array in PHP is defined using the array() structure. PHP array initialization is such as:

<ol class="dp-c"><li class="alt"><span><span class="vars">$people</span><span>=</span><span class="keyword">array</span><span>(</span><span class="string">'name'</span><span>,</span><span class="string">'sex'</span><span>,</span><span class="string">'nation'</span><span>,</span><span class="string">'brith'</span><span>);  </span></span></li></ol>

. As for how to display the value of each element in the array, we start from 0 The index, the index number is in square brackets after the variable name, for example:

<ol class="dp-c">
<li class="alt"><span><span><?php    </span></span></span></li>
<li>
<span class="vars">$people</span><span>=</span><span class="keyword">array</span><span>(</span><span class="string">'name'</span><span>,</span><span class="string">'sex'</span><span>,</span><span class="string">'nation'</span><span>,</span><span class="string">'birth'</span><span>);   </span>
</li>
<li class="alt">
<span class="func">echo</span><span> </span><span class="vars">$people</span><span>[2];   </span>
</li>
<li><span>?> </span></li>
</ol>

The $people[2] output by copying the code shows nation (the first item in the index counts from 0). In addition to supporting numerically indexed arrays, PHP also supports related arrays. The so-called correlation array means that you can customize keywords to replace unintuitive numeric indexes, such as:

<ol class="dp-c">
<li class="alt"><span><span><?php    </span></span></span></li>
<li>
<span class="vars">$peoples</span><span>=</span><span class="keyword">array</span><span>(</span><span class="string">'xm'</span><span>=></span><span class="string">'name'</span><span>,</span><span class="string">'xb'</span><span>=></span><span class="string">'sex'</span><span>,</span><span class="string">'mz'</span><span>=></span><span class="string">'nation'</span><span>,</span><span class="string">'cs'</span><span>=></span><span class="string">'birth'</span><span>);   </span>
</li>
<li class="alt">
<span class="func">echo</span><span> </span><span class="vars">$peoples</span><span>[</span><span class="string">'cs'</span><span>];   </span>
</li>
<li><span>?> </span></li>
</ol>

Copy the code and use the correlation array to make the output selection intuitive (no need to pre- Calculate the index number and then output), use the "=>" symbol between the defined keyword and value. According to the two display methods of PHP array elements, numbers can be automatically created directly without array() declaration and initialization like variables. For example,

<ol class="dp-c">
<li class="alt"><span><span class="vars">$people</span><span>[0]=</span><span class="string">'name'</span><span>;   </span></span></li>
<li>
<span class="vars">$people</span><span>[1]=</span><span class="string">'sex'</span><span>;   </span>
</li>
<li class="alt">
<span class="vars">$people</span><span>[2]=</span><span class="string">'nation'</span><span>;   </span>
</li>
<li>
<span class="vars">$people</span><span>[3]=</span><span class="string">'brith'</span><span>;  </span>
</li>
</ol>

copy code or

<ol class="dp-c">
<li class="alt"><span><span class="vars">$peoples</span><span>[</span><span class="string">'xm'</span><span>]=</span><span class="string">'name'</span><span>;   </span></span></li>
<li>
<span class="vars">$peoples</span><span>[</span><span class="string">'xb'</span><span>]=</span><span class="string">'sex'</span><span>;   </span>
</li>
<li class="alt">
<span class="vars">$peoples</span><span>[</span><span class="string">'mz'</span><span>]=</span><span class="string">'nation'</span><span>;   </span>
</li>
<li>
<span class="vars">$peoples</span><span>[</span><span class="string">'cs'</span><span>]=</span><span class="string">'birth'</span><span>; </span>
</li>
</ol>

copy code. The size of the array changes dynamically according to the number of elements added.

http://www.bkjia.com/PHPjc/445771.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/445771.htmlTechArticlePHP has powerful functions, and more and more people are using it. Here we will give you details on PHP array initialization introduction. From ASP to PHP, I feel that one of the strengths of PHP is the built-in functions...