PHP应用：老生常谈PHP 文件写入和读取(必看篇)

<?php
   $fp = fopen("C:\wamp64\www\text.txt",'w');
?>

<?php
  $fp = fopen("C:/wamp64/www/text.txt",'w');
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'w');
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'w');
  fwrite($fp,'在写模式下写入');
  fclose($fp);
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');
  fwrite($fp,'在读模式下写入');
  fclose($fp);
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'r+');
  fwrite($fp,'r+ mode');
  fclose($fp);
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'a+');
  fwrite($fp,'a+ mode');
  fclose($fp);
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'w+');
  fwrite($fp,'w+ mode');
  fclose($fp);
?>

<?php
   $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
   $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');//打开文件
   if(file_exists("$DOCUMENT_ROOT/text.txt")){//当文件存在时,才读取内容
     while(!feof($fp)){//判断文件指针是否到达末尾
        $c = fgetc($fp);//每执行一次fgetc(),文件指针就向后移动一位
        echo $c;//输出获取到的字节
      }
    }
   fclose($fp);//关闭文件
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');
  echo fgetc($fp);//只做一次输出
  close($fp);
?>

<?php
   $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
   $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');
   echo fgetc($fp);//连续做三次输出
   echo fgetc($fp);
   echo fgetc($fp);
   fclose($fp);
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');
  echo fread($fp, 3);//一次输出三个字节即一个汉字字符(UTF-8)
  fclose($fp);
?>

echo fread($fp, 6);

<?php
    $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT']
    $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');//打开文件
    if(file_exists("$DOCUMENT_ROOT/text.txt")){//当文件存在时,才读取内容
     while(!feof($fp)){//判断文件指针是否到达末尾
       $line = fgets($fp);//返回一行文本,并将文件指针移动到下一行头部
       echo $line."<br/>";//输出获取到的一行文本
     }
    }
    fclose($fp);//关闭文件
?>

$line = fgets($fp,10);

<?php
   $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
   $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');
   fpassthru($fp);
   fclose($fp);
?>

<?php
  $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
  $file_array = file("$DOCUMENT_ROOT/text.txt");//取到文件数组
  foreach ($file_array as $value) {//输出数组元素
    echo $value."<br/>";
  }
?>

<?php
     $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
     function print_file_pointer($fp){//定义一个打印文件指针位置的函数
       echo " <br/>//此时文件指针的位置：";
       echo ftell($fp)."<br/>";
     }
     $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');
     echo fgetc($fp);//通过fgetc连续输出三个字节
     echo fgetc($fp);
     echo fgetc($fp);
     print_file_pointer($fp);//打印此刻文件指针的位置
     
     echo fread($fp,6);//通过fread一次输出6字节
     print_file_pointer($fp);//打印此刻文件指针的位置
     
     echo fgets($fp); //通过fgets输出一整行
     print_file_pointer($fp);//打印此刻文件指针的位置
     
     fpassthru($fp); //一次性输出全部内容
     print_file_pointer($fp);//打印此刻文件指针的位置
     
     fseek($fp, 33);//使文件指针移动到33字节位置
     print_file_pointer($fp);//打印此刻文件指针的位置
     
     rewind($fp);//使文件指针移动到0字节位置(初始位置)
     print_file_pointer($fp);//打印此刻文件指针的位置
$fclose($fp);
?>

<?php
   $DOCUMENT_ROOT = $_SERVER['DOCUMENT_ROOT'];
   $fp = fopen("$DOCUMENT_ROOT/text.txt",'r');
   while(!feof($fp)){
    echo fgets($fp);
    echo ftell($fp);
   }
   fclose($fp);
?>