PHP常用功能，php

PHP常用功能，php

1.PHP字符串

• 字符串声明 变量=''或者""（一般情况会使用单引号，因为写起来会比较方便）

<span>$str</span> = 'Hello PHP'<span>;
</span><span>echo</span> <span>$str</span>;

• strpos 计算字符在字符串中的位置（从0开始）

<span>$str</span> = 'Hello PHP'<span>;
</span><span>echo</span> <span>strpos</span>(<span>$str</span>,'o');  <span>//</span><span>计算字符在字符串中的位置</span>
<span>echo</span> '<br/>'<span>;
</span><span>echo</span> <span>strpos</span>(<span>$str</span>,'PH');

• substr 截取字符串

<span>$str</span> = 'Hello PHP'<span>;
</span><span>//</span><span>截取字符串</span>
<span>$str1</span> = <span>substr</span>(<span>$str</span>,2,3); <span>//</span><span>从2位置开始截取，截取长度为3的字符串</span>
<span>echo</span> <span>$str1</span>;

不传入长度参数的话，会从指定位置一直截取到字符串的末尾

• str_split 分割字符串 固定长度的分割（默认长度为1）

<span>$str</span> = 'Hello PHP'<span>;
</span><span>//</span><span>分割字符串</span>
<span>$result</span> = <span>str_split</span>(<span>$str</span>);   <span>//</span><span>将结果保存到一个数组中</span>
<span>print_r</span>(<span>$result</span>);  <span>//</span><span>使用print_r输入一个数组</span>
<span>echo</span> '<br/>'<span>;
</span><span>$result1</span> = <span>str_split</span>(<span>$str</span>,2<span>);
</span><span>print_r</span>(<span>$result1</span>);

• explode(分割字符,待分割的字符串) 按照空格进行分割

<span>$str</span> = 'Hello PHP Java C# C++'<span>;
</span><span>$result</span> = <span>explode</span>(' ',<span>$str</span><span>);
</span><span>print_r</span>(<span>$result</span>);

• 字符串的连接

<span>$str</span> = 'Hello PHP Java C# C++'<span>;
</span><span>//</span><span>字符串的连接</span>
<span>$num</span> = 100<span>;
</span><span>$str1</span> = <span>$str</span>.'<br/>Objective-C '.<span>$num</span><span>;
</span><span>echo</span> <span>$str1</span><span>;
</span><span>echo</span> '<br/>'<span>;
</span><span>$str2</span> = "<span>$str</span><br/>Objective-C <span>$num</span>";    <span>//</span><span>另一中简便的写法</span>
<span>echo</span> <span>$str2</span>;

2.PHP数组

• 数组的声明 PHP的数组动态性非常好，可以存所有类型的数据

<span>//</span><span>数组的声明方式</span>
<span>$arr</span> = <span>array</span><span>();
</span><span>$arr</span>[0] = 'Hello'<span>;
</span><span>$arr</span>[1] = 'World'<span>;
</span><span>$arr</span>[2] = 2<span>;
</span><span>$arr</span>[3] = 3.14<span>;
</span><span>print_r</span>(<span>$arr</span>);

• array_push()//添加一个元素
• array_pop()//删除最后一个元素

<span>$arr</span> = <span>array</span><span>();
</span><span>for</span>(<span>$i</span>=0;<span>$i</span><100;<span>$i</span>++<span>){
    </span><span>array_push</span>(<span>$arr</span>,'Item'.<span>$i</span><span>);
}
</span><span>print_r</span>(<span>$arr</span>);

• 通过键值对（Key-Value）方式存储数据

<span>$arr</span> = <span>array</span><span>();
</span><span>$arr</span>['H'] = 'Hello'<span>;
</span><span>$arr</span>['W'] = 'World'<span>;
</span><span>print_r</span>(<span>$arr</span><span>);
</span><span>echo</span> '<br/>'<span>;
</span><span>echo</span> <span>$arr</span>['H'];

　 输出： 　 Array ( [H] => Hello [W] => World ) 　 Hello

• 不仅可以把PHP数组当成一个Array用，还可以当成一个Map用
• 数组初始化

<span>$arr</span> = <span>array</span>('H'=>'Hello','W'=>'World');    <span>//</span><span>PHP数组初始化</span>
<span>print_r</span>(<span>$arr</span>);

• 可以同时存在数组小标，以及键值对

<span>$arr</span> = <span>array</span>(0=>'Make',1=>'Tom','H'=>'Hello','W'=>'World'<span>);
</span><span>print_r</span>(<span>$arr</span><span>);
</span><span>echo</span> '<br/>'<span>;
</span><span>echo</span> <span>$arr</span>[0<span>];
</span><span>echo</span> '<br/>'<span>;
</span><span>echo</span> <span>$arr</span>['W'];

     输出：     Array ( [0] => Make [1] => Tom [H] => Hello [W] => World )  　 Make 　 World