Question

我有行

abc
def
ghi
jkl
mno
pqr
xyz

我想取前4行并删除它们？

我正在使用文件

$datafile="/var/www/html/test/data/$data";
$fp = fopen($datafile,"r");

我被困在这里!!如何移动指针，如何使用数组或任何缓冲区？

Answer 1

$array = file("/var/www/html/test/data/$data");
$array = array_slice($array, 4);

Answer 2

您可以使用file_get_contents()获取文件的内容，然后使用preg_split()将其转换为数组。一旦你有一排线;只需使用array_slice()从您想要的索引中切割数组... 在您的情况下，4 。下面的代码显示了......

<?php

    // THE TEXT FILE TO BE READ:
    $targetFile             = "/var/www/html/test/data/$data";

    // GET THE CONTENTS OF THE FILE & STORE IT IN A VARIABLE (IF IT EXISTS)
    $strFileContents        = null;
    if(file_exists($targetFile)){
        $strFileContents    = file_get_contents($targetFile);
    }

    // EVERY LINE IN A IS TERMINATED BY A NEW LINE CHARACTER.... WE KNOW THAT.
    // SO WE SPLIT THE CONTENTS OF THE FILE USING THIS KNOWLEDGE...
    if(!is_null($strFileContents)){
        $arrFileLines   = preg_split("#\n#", $strFileContents);

        // SELECT ALL ELEMENTS FROM THE 4TH ELEMENT TILL THE END
        $arrResultant   = array_slice($arrFileLines, 4);

        // CONVERT THE ARRAY BACK TO STRING...
        $strBuffer      = implode("\n", $arrResultant);

        // RE-SAVE THE FILE BACK...
        file_put_contents($targetFile, $strBuffer);
    }

甚至更简洁;

<?php

    // THE TEXT FILE TO BE READ:
    $targetFile             = "/var/www/html/test/data/$data";
    if(file_exists($targetFile)){
        $arrFileLines       = file($targetFile);
        if(!empty($arrFileLines) && count($arrFileLines) > 4){
            // SELECT ALL ELEMENTS FROM THE 4TH ELEMENT TILL THE END
            $arrResultant   = array_slice($arrFileLines, 4);

            // CONVERT THE ARRAY BACK TO STRING...
            $strBuffer      = implode("", $arrResultant);

            // RE-SAVE THE FILE BACK...
            file_put_contents($targetFile, $strBuffer);

        }
    }

干杯......祝你好运; - ）

指针移动到行并删除它们在PHP，我怎么做？

2 个答案: