php一些功能强大的字符串处理函数总结
php一些功能强大的字符串处理函数总结
列举几个php语言中被遗忘的一些但功能非常强大的字符串处理函数，这里就不对其用法一个个举例了，感兴趣的朋友可以自己测试。
(PHP 4 >= 4.0.4, PHP 5)
1、ctype_alnum
检测是否是只包含[A-Za-z0-9]
2、ctype_alpha
检测是否是只包含[A-Za-z]
3、ctype_cntrl
检查是否是只包含类是"\r\b\t"之类的字符控制字符
4、ctype_digit
检查时候是只包含数字字符的字符串（0-9）
5、ctype_graph
检查是否是只包含有可以打印出来的字符（除了空格）的字符串
6、ctype_lower
检查是否所有的字符都是英文字母，并且都是小写的
7、ctype_print
检查是否是只包含有可以打印出来的字符的字符串
8、ctype_punct
检查是否是只包含非数字/字符/空格的可打印出来的字符
9、ctype_space
检查是否是只包含类是"\r\b\t"之类的字符和空格
10、ctype_upper
检查是否所有的字符都是英文字母，并且都是大写的
11、ctype_xdigit
检查是否是16进制的字符串，只能包括"0123456789abcdef"
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