去空格或其他字符

trim

$str ="\r\nHello World!\r\n";
echo trim($str);

rtrim(别名chop())

ltrim

dirname

例:
echo dirname("f://www/a/b/1.php");
//返回目录  f://www/a/b

字符串生成与转换

str_pad

例:
$str = "hahaha";
echo str_pad($str,10,"@")
//输出  hahaha@@@@

str_report

例:
echo str_repeat("$",5);
//返回 $$$$$

str_split

例:
print_r(str_split("Hello"));
//返回Array ( [0] => H [1] => e [2] => l [3] => l [4] => o )

strrev

例:
echo strrev("hahaha");
//返回  ahahah

wordwrap

str_shuffle()

parse_str()

parse_str("id=23&name=John%20Adams",$myArray);
print_r($myArray);
//Array ( [id] => 23 [name] => John Adams )

number_format()

例:
echo number_format(222222222);
//222,222,222

大小写转换

strtolower()

strtoupper()

ucfirst()

ucwords()

html标签关联

htmlentities()

$str ="John & 'Adams'";
echo htmlentities($str, ENT_COMPAT);

htmlspecialchars()

nl2br()

echo nl2br("ds\ndsa");//\n转换为换行

strip_tags()

echo strip_tags("<br/>dsdsa\n");//dsdsa

addcslashes()

$str = "Hello, my name is John Adams.";
echo $str;
echo "<br/>";
echo addcslashes($str,'m');
//Hello, my name is John Adams.
//Hello, \my na\me is John Ada\ms.

stripcslashes()

addslashes()

例
$str = "Who's John Adams?";
echo addslashes($str);
//Who\'s John Adams?

stripslashes()

例
$str = "Who\'s John Adams?";
echo stripcslashes($str);
//Who's John Adams?

quotemeta()

例
$str = "Hello world. (can you hear me?)";
echo quotemeta($str);
//Hello world\. \(can you hear me\?\

chr()

echo chr(052);//*

ord()

echo ord("hello");//104

字符串比较

strcasecmp()

echo strcasecmp("Hello world!","HELLO WORLD!");
//0

strcmp()

strncmp()

int strncmp ( string $str1 , string $str2 , int $len )

strncasecmp()

strnatcmp()

int strnatcmp ( string $str1 , string $str2 )

strnatcasecmp()

int strnatcasecmp ( string $str1 , string $str2 )

字符串切割与拼接

chunk_split()

str chunk_split(str $body[,int $len[,str $end]])

strtok()

str strtok(str $str,str $token)

explode()

array explode(str $sep,str $str[,int $limit])

implode()

string implode ( string $glue , array $pieces )

substr()

string substr ( string $string , int $start [, int $length ] )

字符串查找替换

str_replace()

echo str_replace('查找的字符串','替换的字符串','主字符串-(查找的字符串)');//替换字符串

str_ireplace()

与上个相反

substr_count()

echo substr_count('aaaaaaa','a');//7

substr_replace()

echo substr_replace('abcdefg','123',1);//a123
echo substr_replace('abcdefg','123',1,4);//a123gf

similar_text()

echo similar_text('abcde','abc');//3

strrchr() == strchr()

echo strrchr('abc123abc456','abc');//abc456

strstr()

echo strstr('abc123abc456','abc');//abc123abc456

stristr()

echo stristr('11abc123abc456','abc');//abc123abc456

strtr()

echo strtr('11abc123abc456','abc','bcd');//11bcd123bcd456

strpos()

echo strpos('11abc123abc456','abc');//2 

stripos()

同上

strrpos()

同上

strripos()

strspn()

strcspn()

字符串统计

str_word_count()

echo str_word_count('acsa sas');//2  统计字符串含有的单词数

strlen()

count_chars()

var_dump(count_chars('sdasdsagf'));

字符串编码

md5()

"$str = ""Hello"";
echo md5($str);
"

json_encode()

json_decode()

ini_get