nl2br
功能:化换行符为<br>
<?php
$str = "cat isn't \n dog";
$result = nl2br($str);
echo $result;
rtrim
功能:清除右边的空白
<?php
$str = "Hello world ";
echo strlen($str)."<br>";
$result = rtrim($str);
echo strlen($result);
strip_tags
功能:清除字符串中html和php的标记
<?php
$str = "<font color = 'red'>Hello world</font>";
$result = strip_tags($str);
echo $result;
strtolower 与 strtoupper
功能:转换成大小写
<?php
$str = "Hello World!";
$result = strtolower($str);
echo $result."<br>";
$result = strtoupper($str);
echo $result;
trim
功能:去除首尾空格
<?php
$str = " Hello World! ";
$result = trim($str);
echo $str."<br>";
echo $result."<br>";
echo strlen($str)."<br>";
echo strlen($result);
str_ireplace
功能:替换
<?php
$str = "zhang san";
$result = str_ireplace("zhang","li",$str);
echo $str."<br>";
echo $result;
str_repeat
功能:将一个字符串重复多遍
<?php
$str = "Hello jiqing!";
$result = str_repeat($str,4);
echo $str."<br>";
echo $result;
str_replace
功能:区分大小写的替换
<?php
$str = "hello jiqing!";
$result1 = str_ireplace("Hello","Hi",$str); //不区分大小写
$result2 = str_replace("Hello","Hi",$str); //区分大小写
echo $str."<br>";
echo $result1."<br>";
echo $result2."<br>";
str_word_count
功能:返回字符串中单词的个数
<?php
$str = "hello jiqing a!";
$result1 = str_word_count($str); //返回个数
$result2 = str_word_count($str,1); //返回数组
echo $str."<br>";
echo $result1."<br>";
print_r($result2);
strlen
功能:返回字符串长度
<?php
$str = "hello jiqing a!";
$result = strlen($str);
echo $result;
substr_count
功能:计算一个字符串在另一个字符串中的个数
<?php
$str = "hello jiqing ,hello jim!";
$result = substr_count($str,"hello");
echo $result;
substr_replace
功能:从某个位置开始替换
<?php
$str = "hello jiqing ,hello jim!";
$result = substr_replace($str,"zhangsan",6);
echo $result."<br>";
$result = substr_replace($str,"zhangsan",6,6);//从某个位置替换,替换几个字符串
echo $result;
substr
功能:获取子字符串
<?php
$str = "abcdef";
$result = substr($str,0,1); //从第0个开始,获取1个
echo $result."<br>";
$result = substr($str,0,-1);//从第0个开始,获取到除了最后一个的字符串
echo $result."<br>";
$result = substr($str,2,-1);//从第2个开始,获取到除了最后一个的字符串
echo $result."<br>";
$result = substr($str,-3,-1);//从第-3个开始,获取到除了最后一个的字符串
echo $result."<br>";
$result = substr($str,-3,1);//从第-3个开始,获取到除了最后一个的字符串
echo $result."<br>";
implode
功能:将数组转化为字符串
<?php
$array = array("2016","6","3");
$date = implode("/",$array);
echo $date;
md5
功能:对字符串进行md5加密
<?php
$str = "Hello world";
$result = md5($str);
echo $result;