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HomeBackend DevelopmentPHP Tutorial【转】PHP运用中的八种常见文件操作方式

【转】PHP应用中的八种常见文件操作方式
PHP 独特的语法混合了 C、Java、Perl 以及 PHP 自创新的语法。 PHP安装它可以比 CGI 或者 Perl 更快速的执行动态网页。用PHP做出的动态页面与其他的编程语言相比,PHP是将程序嵌入到HTML文档中去执行,执行效率比完全生成HTML标记的CGI要高许多;PHP还可以执行编译后代码,编译可以达到加密和优化代码运行,使代码运行更快。PHP具有非常强大的功能,所有的CGI的功能PHP都能实现,而且支持几乎所有流行的数据库以及操作系统。
  文件和目录的操作
  PHP处理本地服务器上的文件和目录是非常方便的,但有时候会出现权限和路径相关的问题
  1.打开文件
  resource fopen ( string filename, string mode [, bool use_include_path [, resource zcontext]] )
  $handle = fopen(filename,mode)//打开文件,返回代表此文件的资源的句柄
  文件名称可以使用相对路径或者绝对路径也可以使用网络协议模式,打开模式具有r\r+\w\w+\a\a+\x\x+\b 在操作二进制文件时如果没有指定 'b' 标记,可能会碰到一些奇怪的问题,包括坏掉的图片文件以及关于 \r\n 字符的奇怪问题。
  为移植性考虑,强烈建议在用 fopen() 打开文件时总是使用 'b' 标记。
  以下是几种打开文件的方式
  $fp = @fopen('log.txt',"rb");
  $fp = @fopen('../log.txt',"rb");
  $fp = @fopen("http://www.runer.com.cn/default.htm","rb");//还可以使用ftp和ghoper等协议,必须启用php.ini文件中的allow_url_fopen选项
  ////////////////////////////代码部分////////////////////////////////////////
  $filename1 = "userinfo.txt";//目录下或include_path中存在这个文件
  $filename2 = "test.txt";//目录下或include_path并不存在这个文件
  $resource1 = fopen($filename1,"rb");
  @$resource2 = fopen($filename2,"rb");//因为目录中不存在这个文件,并且并未使用或include_path寻找包含文件所在路径则此操作会报错,[email protected]
  if($resource1)
  echo "打开文件{$filename1}成功";
  if([email protected]($filename2,"r"))
  echo "打开文件{$filename2}不成功";
  //////////////////////////////////////////////////////////////////////////
  ---------------------输出结果----------------------------------------
  打开文件userinfo.txt成功
  ---------------------------------
  2.使用完毕文件后,要显式的告诉PHP已经使用完文件,让操作系统确保将文件的所有内容正确地从缓冲区刷新到硬盘
  使用fclose()关闭文件,
  bool fclose ( resource handle )//关闭一个已打开的文件指针
  3.读取文件,fopen函数的mode参数允许读取,PHP提供了几个函数从文件读取数据
  string fgets ( int handle [, int length] )从文件指针中读取一行,在二进制文件上尝试fgets会产生不可预测的结果
  如果不指定长度,默认读取1K数据,碰到换行符(包括在返回值中)、EOF 或者已经读取了 length - 1 字节后停止
  string fgetss ( resource handle [, int length [, string allowable_tags]] )从文件指针中读取一行并过滤掉 HTML 标记
  fgetc()读取单个字符
  fread()读取任意二进制数据
  ////////////////////////////代码部分////////////////////////////////////////
  $handle = fopen ("test.jpg", "rb");
  $c;
  while (!feof($handle)) {
  $contents .= @fread($handle, 8192);//循环读取并将其合并为一个大块文件
  }
  fclose($handle);
  //////////////////////////////////////////////////////////////////////////
  ---------------------输出结果----------------------------------------
  ---------------------------------
  4.判断文件读取的状态
  每个文件句柄都有一个文件指针,或者一个指出下一个操作将在文件中哪里发生的游标,根据fopen函数的mode参数
  文件指针最初位于文件的开头(0),或者文件的末尾
  feof()可以判断文件是否已经到末尾(到末尾后函数返回TRUE)
  filesize()函数返回文件的大小 5.写入文件
  fwrite()函数执行文件写入
  ////////////////////////////代码部分////////////////////////////////////////
  $filename = 'test.txt';
  $somec;
  // 首先我们要确定文件存在并且可写。
  if (is_writable($filename)) {
  // 在这个例子里,我们将使用添加模式打开$filename,
  // 因此,文件指针将会在文件的开头,
  // 那就是当我们使用fwrite()的时候,$somecontent将要写入的地方。
  if (!$handle = fopen($filename, 'a')) {
  echo "不能打开文件 $filename";
  exit;
  }
  // 将$somecontent写入到我们打开的文件中。
  if (fwrite($handle, $somecontent) === FALSE) {
  echo "不能写入到文件 $filename";
  exit;
  }
  echo "成功地将 $somecontent 写入到文件$filename";
  fclose($handle);
  } else {
  }
  echo "文件 $filename 不可写";
  //////////////////////////////////////////////////////////////////////////
  ---------------------输出结果----------------------------------------
  成功地将 添加这些文字到文件 写入到文件test.txt
  ---------------------------------
  对于二进制数据,必须指定第三个参数,它包含写入到磁盘的数据字节数
  $result = @fwrite($fp,$binary_data,mb_strlen($binary_data,'8bit'));
  6.文件权限和其他信息
  is_readable()//判断文件是否可读
  is_writeable()//判断文件是否可写
  is_writable()//判断文件是否可写
  fileperms()//判断文件的权限(UNIX风格的文件权限测试函数)
  file_exists()//是否存在这个文件
  fileowner()//判断文件所属用户
  filegroup()//判断文件所属组
  7.删除和重命名文件
  unlink()//删除文件
  rename()//重命名文件
  8.访问目录
  目录访问建议使用前向斜线"/",兼容windows和unix系统
  basename()//返回不包括路径信息的文件名
  dirname()//返回文件名的目录部分
  realpath()//接受相对路径,返回文件的绝对路径
  pathinfo()//提取给定路径的目录名,基本文件名和扩展名
  opendir()//打开目录,返回资源句柄
  readdir()//读取目录项
  rewinddir()//将读取指针返回开头
  closedir()//关闭读取句柄
  chdir()//改变当前脚本执行期间的当前工作目录
  mkdir()//创建目录
  rmdir()删除目录
  ////////////////////////////代码部分////////////////////////////////////////
  //////////////////////////////////////////////////////////////////////////
  ---------------------输出结果----------------------------------------
  filename: web : filetype: dir
  filename: study : filetype: di

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