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探讨各种PHP字符串函数的总结分析

Jun 06, 2016 pm 08:30 PM
php String functions

本篇文章是对各种PHP字符串函数进行了详细的总结与分析,需要的朋友参考下

PHP字符串函数包括查找字符位置函数;提取子字符函数;替换字符串;字符长度;比较字符函数;分割成数组字符;去除空格等等。

PHP语言中的字符串函数也是一个比较易懂的知识。今天我们就为大家总结了将近12种PHP字符串函数,希望对又需要的朋友有所帮助,增加读者朋友的PHP知识库。


1查找字符位置函数:
strpos($str,search,[int]):查找search在$str中的第一次位置从int开始;
stripos($str,search,[int]):函数返回字符串在另一个字符串中第一次出现的位置。该函数对大小写不敏感 strrpos($str,search,[int]):查找search在$str中的最后一次出现的位置从int开始
strripos($str,search,[int]):同上,该函数对大小写不敏感

2、提取子字符串函数(双字节)
substr($str,int start[,int length]):从$str中strat位置开始提取[length长度的字符串]。
strstr($str1,$str2):从$str1(第一个的位置)搜索$str2并从它开始截取到结束字符串;若没有则返回FALSE。
stristr() 功能同strstr,只是不区分大小写。
strrchr() 从最后一次搜索到的字符处返回;用处:取路径中文件名

3、替换字符串的PHP字符串函数
str_replace(search,replace,$str):从$str中查找search用replace来替换
str_ireplace(search,replace,$str):同上,该函数对大小写不敏感
strtr($str,search,replace):这个函数中replace不能为"";
substr_replace($Str,$rep,$start[,length]):$str原始字符串,$rep替换后的新字符串,$start起始置,$length替换的长度,美国空间,香港服务器,该项可选

4、字符长度
int strlen($str)

5、比较字符函数
int strcmp($str1,$str2):$str1>=strcasecmp() 同上(不分大小写)
strnatcmp("4","14") 按自然排序比较字符串
strnatcasecmp() 同上,(区分大小写)

6、分割成数组的PHP字符串函数
str_split($str,len):把$str按len长度进行分割返回数组
split(search,$str[,int]):把$str按search字符进行分割返回数组int是分割几次,后面的将不分割 expload(search,$str[,int])

7、去除空格:
ltrim()、rtrim()、trim()

8、加空格函数
chunk_split($str,2):向$str字符里面按2个字符就加入一个空格;

9、chr、ord--返回指定的字符或ascii

10、HTML代码有关函数
nl2br():使\n转换为

strip_tags($str[,'

']):

去除HTML和PHP标记

在$str中所有HTML和PHP代码将被去除,可选参数为html和PHP代码作用是将保留可选参数所写的代码。
如:echo strip_tags($text, '

');
htmlspecialchars($str[,参数]):页面正常输出HTML代码参数,是转换方式

11、字符大小写转换的PHP字符串函数
strtolower($str): 字符串转换为小写
strtoupper($str): 字符串转换为大写
ucfirst($str): 将函数的第一个字符转换为大写
ucwords($str): 将每个单词的首字母转换为大写

12、数据库相关的PHP字符串函数
addslashes($str):使str内单引号(')、双引号(")、反斜线(\)与 NUL
字符串转换为\',\",\\。
magic_quotes_gpc = On :自动对 get,post,cookie的内容进行转义
get_magic_quotes_gpc():检测是否打开magic_quotes_gpc
stripslashes(): 去除字符串中的反斜杠

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