PHP常用字符串处理函数

"readonly"</span> name=<span class="hljs-string">"code"</span> class=<span class="hljs-string">"php"</span>> 
<span class="hljs-regexp">//</span> <span class="hljs-number">1</span>.strstr(<span class="hljs-variable">$string</span>, <span class="hljs-variable">$find</span>) 查找字符串的首次出现，返回从<span class="hljs-variable">$find</span>到￥string结尾的字符串，区分大小写，不区分大小写：stristr()
<span class="hljs-variable">$s1</span> = <span class="hljs-string">'abcdcefg'</span>;
<span class="hljs-variable">$r</span> = strstr(<span class="hljs-variable">$s1</span>, <span class="hljs-string">'f'</span>);
<span class="hljs-variable">$r2</span> = strstr(<span class="hljs-variable">$s1</span>, <span class="hljs-string">'c'</span>);
echo <span class="hljs-variable">$r</span>.<span class="hljs-string">'<br />'</span>;    <span class="hljs-regexp">//fg</span>
var_dump(<span class="hljs-variable">$r2</span>); <span class="hljs-regexp">//string</span>(<span class="hljs-number">6</span>) <span class="hljs-string">"cdcefg"</span>
// <span class="hljs-number">2</span>.strpos(),获取字符串首次出现的位置，返回字符串首次出现的数字位置,区分大小写stripos()
<span class="hljs-variable">$s1</span> = <span class="hljs-string">'abcdcefg'</span>;
<span class="hljs-variable">$r</span> = strpos(<span class="hljs-variable">$s1</span>, <span class="hljs-string">'c'</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//int</span>(<span class="hljs-number">2</span>)
//<span class="hljs-number">3</span>.strrpos(),获取字符串最后一次出现的位置，区分大小写strripos()
<span class="hljs-variable">$s1</span> = <span class="hljs-string">'abcdcefg'</span>;
<span class="hljs-variable">$r</span> = strrpos(<span class="hljs-variable">$s1</span>, <span class="hljs-string">'c'</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//int</span>(<span class="hljs-number">4</span>)
// <span class="hljs-number">4</span>.<span class="hljs-keyword">substr</span>();截取字符串，返回字符串的子串
<span class="hljs-variable">$s1</span> = <span class="hljs-string">'abcdcefg'</span>;
<span class="hljs-variable">$r</span> = <span class="hljs-keyword">substr</span>(<span class="hljs-variable">$s1</span>, <span class="hljs-number">0</span>, <span class="hljs-number">2</span>);
<span class="hljs-variable">$r2</span> = <span class="hljs-keyword">substr</span>(<span class="hljs-variable">$s1</span>, -<span class="hljs-number">3</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">2</span>) <span class="hljs-string">"ab"</span>
var_dump(<span class="hljs-variable">$r2</span>); <span class="hljs-regexp">//string</span>(<span class="hljs-number">3</span>) <span class="hljs-string">"efg"</span>
// <span class="hljs-number">5</span>.strchr() strstr()函数的别名，用法同strstr();
<span class="hljs-regexp">//</span> <span class="hljs-number">6</span>.strrchr(<span class="hljs-variable">$string</span>, <span class="hljs-variable">$find</span>),查找字符串最后一次出现，返回从<span class="hljs-variable">$find</span>到<span class="hljs-variable">$string</span>结尾的字符串
<span class="hljs-variable">$s1</span> = <span class="hljs-string">'abcdcefg'</span>;
<span class="hljs-variable">$r</span> = strrchr(<span class="hljs-variable">$s1</span>, <span class="hljs-string">'c'</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">4</span>) <span class="hljs-string">"cefg"</span>
// <span class="hljs-number">7</span>.strrev(<span class="hljs-variable">$string</span>)； 字符串翻转，返回字符串反转后的字符串
<span class="hljs-variable">$s1</span> = <span class="hljs-string">'hello, world!'</span>;
<span class="hljs-variable">$r</span> = strrev(<span class="hljs-variable">$s1</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">13</span>) <span class="hljs-string">"!dlrow ,olleh"</span>
// <span class="hljs-number">8</span>.strtoupper(<span class="hljs-variable">$string</span>);将字符串中英文字符转换为大写；
<span class="hljs-variable">$s</span> = <span class="hljs-string">'我们，women'</span>;
<span class="hljs-variable">$r</span> = strtoupper(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">14</span>) <span class="hljs-string">"我们，WOMEN"</span>
// <span class="hljs-number">9</span>.strtolower(<span class="hljs-variable">$string</span>);将字符串中英文字符转换为小写；
<span class="hljs-variable">$s</span> = <span class="hljs-string">'我们，WOMEN'</span>;
<span class="hljs-variable">$r</span> = strtoupper(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">14</span>) <span class="hljs-string">"我们，women"</span>
// <span class="hljs-number">10</span>.strtotime();将日期字符串转换为时间戳
<span class="hljs-variable">$s</span> = <span class="hljs-string">'2017-3-26'</span>;
<span class="hljs-variable">$r</span> = strtotime(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//int</span>(<span class="hljs-number">1490482800</span>)
// <span class="hljs-number">11</span>.number_format — 以千位分隔符方式格式化一个数字
<span class="hljs-variable">$s</span> = <span class="hljs-string">'1234567890'</span>;
<span class="hljs-variable">$r</span> = number_format(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">13</span>) <span class="hljs-string">"1,234,567,890"</span>
// <span class="hljs-number">12</span>.str_split — 将字符串转换为数组
<span class="hljs-variable">$s</span> = <span class="hljs-string">'hello'</span>;
<span class="hljs-variable">$r</span> = str_split(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//array</span>(<span class="hljs-number">5</span>) { [<span class="hljs-number">0</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"h"</span> [<span class="hljs-number">1</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"e"</span> [<span class="hljs-number">2</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"l"</span> [<span class="hljs-number">3</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"l"</span> [<span class="hljs-number">4</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"o"</span> }
// <span class="hljs-number">13</span>.str_repeat — 重复一个字符串
echo <span class="hljs-string">'<br />'</span>;
<span class="hljs-variable">$s</span> = <span class="hljs-string">'——'</span>;
<span class="hljs-variable">$r</span> = str_repeat(<span class="hljs-variable">$s</span>, <span class="hljs-number">4</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">24</span>) <span class="hljs-string">"————————"</span>
// <span class="hljs-number">14</span>.str_replace — 子字符串替换
<span class="hljs-variable">$s</span> = <span class="hljs-string">'he——ll0'</span>;
<span class="hljs-variable">$r</span> = str_replace(<span class="hljs-string">'——'</span>, <span class="hljs-string">''</span>, <span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">5</span>) <span class="hljs-string">"hell0"</span>
// <span class="hljs-number">15</span>.str_shuffle — 随机打乱一个字符串
<span class="hljs-variable">$s</span> = <span class="hljs-string">'hello, world!'</span>;
<span class="hljs-variable">$r</span> = str_shuffle(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">13</span>) <span class="hljs-string">"orolh! ,lewdl"</span>
// <span class="hljs-number">16</span>.ip2long — 将一个IPV4的字符串互联网协议转换成数字格式
<span class="hljs-variable">$s</span> = <span class="hljs-string">'127.0.0.1'</span>;
<span class="hljs-variable">$r</span> = ip2long(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//int</span>(<span class="hljs-number">2130706433</span>)
// <span class="hljs-number">17</span>.long2ip — 将一个数字格式的IP转换成IPV4的字符串
<span class="hljs-variable">$s</span> = <span class="hljs-number">2130706433</span>;
<span class="hljs-variable">$r</span> = long2ip(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">9</span>) <span class="hljs-string">"127.0.0.1"</span>
// <span class="hljs-number">18</span>.strval — 获取变量的字符串值
<span class="hljs-variable">$s</span> = <span class="hljs-string">'abc我们'</span>;
<span class="hljs-variable">$r</span> = strval(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//</span> string(<span class="hljs-number">9</span>) <span class="hljs-string">"abc我们"</span>
// <span class="hljs-number">19</span>.substr_count — 计算字串出现的次数
<span class="hljs-variable">$s</span> = <span class="hljs-string">'abcaaaaaa4354jhj我们'</span>;
<span class="hljs-variable">$r</span> = substr_count(<span class="hljs-variable">$s</span>, <span class="hljs-string">'a'</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//int</span>(<span class="hljs-number">7</span>)
// <span class="hljs-number">20</span>.strlen — 获取字符串长度
<span class="hljs-variable">$s</span> = <span class="hljs-string">'abcaaaaaa4354jhj我们'</span>;
<span class="hljs-variable">$r</span> = strlen(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//int</span>(<span class="hljs-number">22</span>)
// <span class="hljs-number">21</span>.explode — 使用一个字符串分割另一个字符串
<span class="hljs-variable">$s</span> = <span class="hljs-string">'a,b,c,d'</span>;
<span class="hljs-variable">$r</span> = explode(<span class="hljs-string">','</span>, <span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//array</span>(<span class="hljs-number">4</span>) { [<span class="hljs-number">0</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"a"</span> [<span class="hljs-number">1</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"b"</span> [<span class="hljs-number">2</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"c"</span> [<span class="hljs-number">3</span>]=> string(<span class="hljs-number">1</span>) <span class="hljs-string">"d"</span> }
// <span class="hljs-number">22</span>.implode — 将一个一维数组的值转化为字符串
<span class="hljs-variable">$arr</span> = [<span class="hljs-string">'a'</span>, <span class="hljs-string">'b'</span>, <span class="hljs-string">'c'</span>, <span class="hljs-string">'d'</span>];
<span class="hljs-variable">$r</span> = implode(<span class="hljs-string">','</span>, <span class="hljs-variable">$arr</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">7</span>) <span class="hljs-string">"a,b,c,d"</span>
// <span class="hljs-number">23</span>.trim — 去除字符串首尾处的空白字符（或者其他字符）
// <span class="hljs-number">24</span>.ltrim — 删除字符串开头的空白字符（或其他字符）
// <span class="hljs-number">25</span>.rtrim(str)  — 删除字符串结尾的空白字符（或其他字符）
// <span class="hljs-number">26</span>.strip_tags — 从字符串中去除 HTML 和 PHP 标记
<span class="hljs-variable">$s</span> = <span class="hljs-string">'<p>hello, world!</p><br />你好，世界'</span>;
<span class="hljs-variable">$r</span> = strip_tags(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">28</span>) <span class="hljs-string">"hello, world!你好，世界"</span>
// <span class="hljs-number">27</span>.chunk_split — 将字符串分割成小块
<span class="hljs-variable">$s</span> = <span class="hljs-string">'abcdefg'</span>;
<span class="hljs-variable">$r</span> = chunk_split(<span class="hljs-variable">$s</span>, <span class="hljs-number">2</span>, <span class="hljs-string">'!'</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">11</span>) <span class="hljs-string">"ab!cd!ef!g!"</span>
<span class="hljs-variable">$r2</span> = chunk_split(base64_encode(<span class="hljs-variable">$s</span>));
var_dump(<span class="hljs-variable">$r2</span>); <span class="hljs-regexp">//string</span>(<span class="hljs-number">14</span>) <span class="hljs-string">"YWJjZGVmZw== "</span>
// <span class="hljs-number">28</span>.htmlspecialchars — Convert special characters to HTML entities
<span class="hljs-variable">$s</span> = <span class="hljs-string">'<p>abcdefg</p>'</span>;
<span class="hljs-variable">$r</span> = htmlspecialchars(<span class="hljs-variable">$s</span>);
var_dump(<span class="hljs-variable">$r</span>);  <span class="hljs-regexp">//string</span>(<span class="hljs-number">26</span>) <span class="hljs-string">"<p>abcdefg</p>"</span>
// <span class="hljs-number">29</span>.<span class="hljs-keyword">ucfirst</span> — 将字符串的首字母转换为大写
// <span class="hljs-number">30</span>.ucwords — 将字符串中每个单词的首字母转换为大写
// <span class="hljs-number">31</span>.addslashes — 使用反斜线引用字符串,返回字符串，该字符串为了数据库查询语句等的需要在某些字符前加上了反斜线。这些字符是单引号（<span class="hljs-string">'）、双引号（"）、反斜线（\）与 NUL（NULL 字符）。
$s = '</span>\abcdefg\/<span class="hljs-string">';
$r = addslashes($s);
var_dump($r);  // "\\abcdefg\\/"
// 32.stripslashes — 反引用一个引用
$s = '</span>\abcd\ef\g\/<span class="hljs-string">';
$r = stripslashes($s);
var_dump($r);  //string(8) "abcdefg/"