Excerpted from PHP manual [8] – String string processing function

简介：本次介绍的是PHP手册中用来对字符串进行各种操作的系统函数，下面天涯把最常用的进行详细说明。

addslashes — 使用反斜线引用字符串
stripslashes — 去除 addslashes() 添加的反斜线

//天涯PHP博客 http://blog.phpha.com
$phpha = 'TianYa say: "Hello World!"';
$phpha2 = addslashes($phpha);
$phpha3 = stripslashes($phpha2);
echo $phpha2 . '
' . $phpha3;
?>
//输出如下：
TianYa say: \"Hello World!\"
TianYa say: "Hello World!"

crc32 — 计算一个字符串的 crc32 多项式
crypt — One-way string encryption (hashing)
echo — 输出一个字符串
explode — 使用一个字符串分割另一个字符串
implode — 用一个字符串连接数组的键值合并成新的字符串

//天涯PHP博客 http://blog.phpha.com
$phpha = 'Hello,World,Hi,Skyline';
$phpha_explode = explode(',', $phpha);
$phpha_implode = implode('+', $phpha_explode);
print_r($phpha_explode);
echo $phpha_implode;
?>
//输出如下：
Array
(
[0] => Hello
[1] => World
[2] => Hi
[3] => Skyline
)
Hello+World+Hi+Skyline

htmlspecialchars — 把特殊字符转换成HTML实体符号
htmlspecialchars_decode — 把HTML实体符号转换陈特殊字符

//天涯PHP博客 http://blog.phpha.com
$phpha = ';
$phpha2 = htmlspecialchars($phpha);
$phpha3 = htmlspecialchars_decode($phpha2);
echo $phpha2;
echo $phpha3;
?>
//输出如下：
//注意：需要在浏览器中“查看网页源代码”
<a href="http://www.php1.cn/">
天涯PHP博客

ltrim — 去除字符串左侧指定的字符（默认为空格）
rtrim — 去除字符串右侧指定的字符（默认为空格）
trim — 去除字符串两侧指定的字符（默认为空格）

//Remove spaces by default
//Tianya PHP blog http://blog.phpha.com
$phpha = ' HelloWorld ';
echo '|' . ltrim($phpha) . ' |
';
echo '|' . rtrim($phpha) . '|
';
echo '|' . trim($phpha) . '|';
?> ;
//The output is as follows:
|HelloWorld |
| HelloWorld|
|HelloWorld|
//Remove the specified characters
//Tianya PHP Blog http://blog.phpha.com
$phpha_com = ' #HelloWorld#';
echo '|' . ltrim($phpha_com, '#') . '|
';
echo '|' . rtrim($phpha_com, '#') . '|< ;br />';
echo '|' . trim($phpha_com, '#') . '|';
?>
//The output is as follows:
|HelloWorld#|
|#HelloWorld|
|HelloWorld |

sprintf — format string

sprintf(format,arg1,arg2,arg++)
format can be of the following types
%% - Returns the percent sign
%b - Binary number
%c - Character according to ASCII value
%d - Signed decimal number
%e - Continuous notation (such as 1.5e+3)
%u - Unsigned decimal number
%f - Floating point number (local settings aware)
%F - Floating point number (not local settings aware)
%o - Octal number
%s - String
%x - Hexadecimal number (lower case letters)
%X - Hexadecimal number (upper case letters)
$str = "Hello";
$number = 123;
$txt = sprintf("%s world. Day number %u",$str,$number);
// Hello world. Day number 123
echo $txt;
?>

str_repeat — Repeat a string a specified number of times

echo str_repeat('Hello', 10);
?>
//The output is as follows:
HelloHelloHelloHelloHelloHelloHelloHelloHello

str_replace — Replace the specified string

echo str_replace("world","John","Hello world!");
$arr = array("blue","red","green","yellow");
print_r(str_replace("red","pink",$arr,$i));
echo "替换次数: $i";
?>
//输出如下：
Hello John!
Array
(
[0] => blue
[1] => pink
[2] => green
[3] => yellow
)
替换次数: 1

str_split — 把字符串分割到数组中

print_r(str_split("Hello",3));
?>
//输出如下：
Array
(
[0] => Hel
[1] => lo
)

strip_tags — 函数剥去 HTML、XML 以及 PHP 的标签
第二个参数为允许的标签，不会被过滤

echo strip_tags("Hello world!", "");
?>
//输出如下：
Hello world!

strpos — Returns the position of the first occurrence of a string in another string, case-sensitive
stripos — Returns the position of the first occurrence of a string in another string, case-insensitive

echo strpos('Hello World', 'Wo'); // 6
echo strpos('Hello World', 'wO'); // Empty
echo stripos('Hello World', ' wO'); // 6
?>

strstr — Search for the first occurrence of one string within another string
stristr — Same as above, case-insensitive
This function returns the rest of the string part (from matching point). Returns false if the searched string is not found

echo strstr('Hello World', 'Wo'); // World
echo strstr('Hello World', 'wO' ); // Empty
echo stristr('Hello World', 'wO'); // World
?>

strlen — Returns the length of the string

echo strlen('http://blog.phpha.com'); // 21
echo strlen('http://www.phpha.com'); // 20
?>

strtolower — 将字符串中大写字母转换为小写
strtoupper — 将字符串中小写字母转换为大写

echo strtoupper('Hello, World!'); // HELLO, WORLD!
echo strtolower('Hello, World!'); // hello, world!
?>

ucfirst — 将整个字符串第一个字母转换为大写
ucwords — 将字符串中每一个单词的首字母转换为大写

echo ucfirst('hello, world!'); // Hello, world!
echo ucwords('hello, world!'); // Hello, World!
?>

md5 — PHP中的MD5加密

// f9ee486a49ebce11b5118ba57ceb9419
echo md5('http://blog.phpha.com');
?>
 以上就是摘自PHP手册[8] – String字符串处理函数的内容，更多相关内容请关注PHP中文网（www.php.cn）！