本文实例总结了PHP常用字符串String函数。分享给大家供大家参考，具体如下：
nl2br
功能：化换行符为
PHP;">
PHP
$str = "cat isn't \n dog";
$result = nl2br($str);
echo $result;
/**结果
cat isn't
dog
*/
rtrim
功能：清除右边的空白
PHP;">
PHP
$str = "Hello world ";
echo strlen($str)."
"; $result = rtrim($str); echo strlen($result); /**结果 14 11 */
"; $result = rtrim($str); echo strlen($result); /**结果 14 11 */
strip_tags
PHP;">
PHP
$str = "Hello world";
$result = strip_tags($str);
echo $result;
/**结果
Hello world
*/
strtolower 与 strtoupper
功能：转换成大小写
PHP;">
PHP
$str = "Hello World!";
$result = strtolower($str);
echo $result."
"; $result = strtoupper($str); echo $result; /**结果 hello world! HELLO WORLD! */
"; $result = strtoupper($str); echo $result; /**结果 hello world! HELLO WORLD! */
trim
PHP;">
PHP
$str = " Hello World! ";
$result = trim($str);
echo $str."
"; echo $result."
"; echo strlen($str)."
"; echo strlen($result); /**结果 Hello World! Hello World! 16 12 */
"; echo $result."
"; echo strlen($str)."
"; echo strlen($result); /**结果 Hello World! Hello World! 16 12 */
str_ireplace
功能：替换
PHP;">
PHP
$str = "zhang san";
$result = str_ireplace("zhang","li",$str);
echo $str."
"; echo $result; /**结果 zhang san li san */
"; echo $result; /**结果 zhang san li san */
str_repeat
功能：将一个字符串重复多遍
PHP;">
PHP
$str = "Hello jiqing!";
$result = str_repeat($str,4);
echo $str."
"; echo $result; /**结果 Hello jiqing! Hello jiqing!Hello jiqing!Hello jiqing!Hello jiqing! */
"; echo $result; /**结果 Hello jiqing! Hello jiqing!Hello jiqing!Hello jiqing!Hello jiqing! */
str_replace
功能：区分大小写的替换
PHP;">
PHP
$str = "hello jiqing!";
$result1 = str_ireplace("Hello","Hi",$str); //不区分大小写
$result2 = str_replace("Hello",$str); //区分大小写
echo $str."
"; echo $result1."
"; echo $result2."
"; /**结果 hello jiqing! Hi jiqing! hello jiqing! */
"; echo $result1."
"; echo $result2."
"; /**结果 hello jiqing! Hi jiqing! hello jiqing! */
str_word_count
功能：返回字符串中单词的个数
PHP;">
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."
"; echo $result1."
"; print_r($result2); /**结果 hello jiqing a! 3 Array ( [0] => hello [1] => jiqing [2] => a ) */
"; echo $result1."
"; print_r($result2); /**结果 hello jiqing a! 3 Array ( [0] => hello [1] => jiqing [2] => a ) */
strlen
功能：返回字符串长度
PHP;">
PHP
$str = "hello jiqing a!";
$result = strlen($str);
echo $result;
/**结果
15
*/
substr_count
功能：计算一个字符串在另一个字符串中的个数
PHP;">
PHP
$str = "hello jiqing,hello jim!";
$result = substr_count($str,"hello");
echo $result;
/**结果
2
*/
substr_replace
功能：从某个位置开始替换
PHP;">
PHP
$str = "hello jiqing,hello jim!";
$result = substr_replace($str,"zhangsan",6);
echo $result."
"; $result = substr_replace($str,6,6);//从某个位置替换，替换几个字符串 echo $result; /**结果 hello zhangsan hello zhangsan,hello jim! */
"; $result = substr_replace($str,6,6);//从某个位置替换，替换几个字符串 echo $result; /**结果 hello zhangsan hello zhangsan,hello jim! */
substr
PHP;">
PHP
$str = "abcdef";
$result = substr($str,1); //从第0个开始，获取1个
echo $result."
"; $result = substr($str,-1);//从第0个开始，获取到除了最后一个的字符串 echo $result."
"; $result = substr($str,2,-1);//从第2个开始，获取到除了最后一个的字符串 echo $result."
"; $result = substr($str,-3,-1);//从第-3个开始，获取到除了最后一个的字符串 echo $result."
"; $result = substr($str,1);//从第-3个开始，获取到除了最后一个的字符串 echo $result."
"; /**结果 a abcde cde de d */
"; $result = substr($str,-1);//从第0个开始，获取到除了最后一个的字符串 echo $result."
"; $result = substr($str,2,-1);//从第2个开始，获取到除了最后一个的字符串 echo $result."
"; $result = substr($str,-3,-1);//从第-3个开始，获取到除了最后一个的字符串 echo $result."
"; $result = substr($str,1);//从第-3个开始，获取到除了最后一个的字符串 echo $result."
"; /**结果 a abcde cde de d */
implode
功能：将数组转化为字符串
PHP;">
PHP
$array = array("2013","6","3");
$date = implode("/",$array);
echo $date;
/**结果
2013/6/3
*/
md5
功能：对字符串进行md5加密
PHP;">
PHP
$str = "Hello world";
$result = md5($str);
echo $result;
/**结果
3e25960a79dbc69b674cd4ec67a72c62
*/
更多关于PHP相关内容感兴趣的读者可查看本站专题：《》、《》、《》、《》、《》、《》、《》及《》
希望本文所述对大家PHP程序设计有所帮助。
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