PHP面试中常见的字符串与文件操作题目

PHP面试中常见的字符串与文件操作题目

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1、PHP翻转中文字符串

function reverse ( $str ) {$r = array ( ) ;for ( $i = 0 ; $i < mb_strlen ( $str ) ; $i ++ ) {$r [ ] = mb_substr ( $str , $i , 1 , 'UTF-8' ) ;}return implode ( array_reverse ( $r ) ) ;}echo reverse ( 'www.phpha.com天涯PHP博客' ) ;//结果：'客博PHP涯天moc.ahphp.wwww'

2、PHP计算URL的文件后缀名

function getext ( $url ) {$data = parse_url ( $url ) ;$path = $data [ 'path' ] ;$info = pathinfo ( $path ) ;return $info [ 'extension' ] ;}echo getext ( 'http://blog.phpha.com/archives/1670.html?id=1670' ) ;//结果：'html'

3、PHP计算两个文件的相对路径

function getrpath ( $path , $conpath ) {$pathArr = explode ( '/' , $path ) ; $conpathArr = explode ( '/' , $conpath ) ;$dismatchlen = 0 ;for ( $i = 0 ; $i < count ( $pathArr ) ; $i ++ ) {if ( $conpathArr [ $i ] != $pathArr [ $i ] ) {$dismatchlen = count ( $pathArr ) - $i ;$arrleft = array_slice ( $pathArr , $i ) ;break ;}}return str_repeat ( '../' , $dismatchlen ) . implode ( '/' , $arrleft ) ;}$a = '/a/b/c/d/e.php' ;$b = '/a/b/12/34/5.php' ;echo getrpath ( $a , $b ) ;//结果：'../../../c/d/e.php'

4、PHP遍历目录下的所有文件和文件夹

function finddir ( $dir ) {$files = array ( ) ;if ( is_dir ( $dir ) ) {if ( $handle = opendir ( $dir ) ) {while ( ( $file = readdir ( $handle ) ) !== false ) {if ( $file != '.' && $file != '..' ) {if ( is_dir ( rtrim ( $dir , '/' ) . '/' . $file ) ) {$files [ $file ] = finddir ( rtrim ( $dir , '/' ) . '/' . $file ) ;} else {$files [ ] = rtrim ( $dir , '/' ) . '/' . $file ;}}}closedir ( $handle ) ;}}return $files ;}print_r ( finddir ( 'F:/Golang/src' ) ) ;/**结果：Array([0] => F:/Golang/src/hello.go[1] => F:/Golang/src/src.exe[test] => Array([0] => F:/Golang/src/test/sss.txt))**/