如何从文件中读取第一行10000行并将它们写入另一行？ PHP

Question

你好，我有这样的代码：

 file1 = file_get_contents("read.txt"); 
$path2 = "write.txt"; 
$file2 = file_get_contents($path2); 
if ($file1 !== $file2){ 
    file_put_contents($path2, $file1); 
    echo "working"; 
} 

我怎样才能从read.txt文件第10000线以上，他们write.txt写？

Answer 1

您可以通过很多方式来读取整个文件，但最好使用流并只读取所需的数据。

<?php 
$source="file.txt"; 
$destination="file2.txt"; 
$requiredLines=10000; 

//compare the modification times, if source is newer than destination - then we do our work 
if(filemtime($source)>filemtime($destination)){   
    //work out maximum length of file, as one line may be the whole file. 
    $filesize = filesize($source); 

    //open file for reading - this doesnt actually read the file it allows us to "stream" it 
    $sourceHandle = fopen($source, "r"); 

    //open file for writing 
    $destinationHandle = fopen($destination, "w"); 

    $linecount=0; 
    //loop through file until we reach the end of the file (feof) or we reach the desired number of lines 
    while (!feof($sourceHandle) && $linecount++<$requiredLines) { 
     //read one line 
     $line = stream_get_line($sourceHandle, $filesize, "\n"); 
     //write the line 
     fwrite($destinationHandle,$line); 
    } 
    //close both files 
    fclose($sourceHandle); 
    fclose($destinationHandle); 
} 

您可以在溪流找到更多的信息在这里：Understanding PHP Streams