//$str = ‘zhang’;

// 行定位符^ 匹配字符串的开始

//$pg = ‘/^abc/’;

//匹配结束的字符串

//$pg = ‘/abc$/’;

//preg_match( $pg, $str, $arr );

//print_r( $arr );

// 匹配单词zhang，单词的前面和后面不能有其他字符串

//$pg = ‘/\bzhang\b/’;

//preg_match( $pg, $str, $arr );

//print_r( $arr );

//$str = ‘TM’;

//字符类匹配TM、Tm、tM、tm

//$pg = ‘/[Tt][Mm]/’;

//preg_match( $pg, $str, $arr );

//print_r( $arr );

//$str = ‘ZhangRong’;//ZhangRong

//选择符有“或”的意思

//$pg = ‘/(Zhang|zhang)Rong/’;

//preg_match( $pg, $str, $arr );

//print_r( $arr );

//$str = ‘azhang’;

//连字符

//$pg = ‘/[a-cA-Z]/’;

//preg_match( $pg, $str, $arr );

//print_r( $arr );

//排除符，^号写在[]里的最前面

//$str = ‘azhang’;

//$pg = ‘/[^a-cA-Z]/’;

//preg_match( $pg, $str, $arr );

//print_r( $arr );

//限定符、点字符

//$pg = ‘/^z.{2}n.+n$/’;

//preg_match( $pg, $str, $arr );

//print_r( $arr );