Need to write at beginning of file with PHP-第2页回答

I'm making this program and I'm trying to find out how to write data to the beginning of a file rather than the end. "a"/append only writes to the end, how can I make it write to the beginning? Because "r+" does it but overwrites the previous data.

$datab = fopen('database.txt', "r+");

Here is my whole file:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
        <title>Facebook v0.1</title>
        <style type="text/css">
            #bod{
                margin:0 auto;
                width:800px;
                border:solid 2px black;
            }
        </style>
    </head>

    <body>
        <div id="bod">
            <?php
                $fname = $_REQUEST['fname'];
                $lname = $_REQUEST['lname'];
                $comment = $_REQUEST['comment'];
                $datab = $_REQUEST['datab'];
                $gfile = $_REQUEST['gfile'];

                print <<<form
                <table border="2" style="margin:0 auto;">
                    <td>
                        <form method="post"  action="">
                              First Name :
                              <input type ="text"
                                         name="fname"
                                         value="">
                              <br>

                              Last Name :
                                <input type ="text"
                                         name="lname"
                                         value="">
                              <br>

                              Comment :
                              <input type ="text"
                                         name="comment"
                                         value="">
                              <br>
                              <input type ="submit" value="Submit">
                        </form>
                    </td>
                </table>
                form;
                if((!empty($fname)) && (!empty($lname)) && (!empty($comment))){
                    $form = <<<come

                    <table border='2' width='300px' style="margin:0 auto;">
                        <tr>
                            <td>
                                <span style="color:blue; font-weight:bold;">
                                $fname $lname :
                                </span>

                                $comment
                            </td>
                        </tr>
                    </table>
                    come;

                    $datab = fopen('database.txt', "r+");
                    fputs($datab, $form);
                    fclose($datab);

                }else if((empty($fname)) && (empty($lname)) && (empty($comment))){
                    print" please input data";
                } // end table

                $datab = fopen('database.txt', "r");

                while (!feof($datab)){
                    $gfile = fgets($datab);
                    print "$gfile";
                }// end of while
            ?>
        </div>
    </body>
</html>

标签： php file append

9条回答

还给你的自由

2楼-- · 2019-01-02 21:38

There is no way to write to the beginning of a file like you think. This is I guess due to reason how OS and HDD are seeing the file. It has got a fixed start and expanding end. If you want to add something in the middle or beggining it requires some sliding. If it is a small file just read it all and do your manipulation and write back. But if not, and if you are always adding to the beginning just reverse line order, consider the end as beginning...

0人赞添加讨论(0) 举报

零度萤火

3楼-- · 2019-01-02 21:40

This code remembers data from the beginning of the file to protect them from being overwritten. Next it rewrites the all the data existing in file chunk by chunk.

$data = "new stuff to insert at the beggining of the file";
$buffer_size = 10000;

$f = fopen("database.txt", "r+");
$old_data_size = strlen($data);
$old_data = fread($f, $old_data_size);
while($old_data_size > 0) {
  fseek($f, SEEK_CUR, -$old_data_size);
  fwrite($f, $data);
  $data = $old_data;
  $old_data = fread($f, $buffer_size);
  $old_data_size = strlen($data);
}
fclose($f);

0人赞添加讨论(0) 举报

怪性笑人.

4楼-- · 2019-01-02 21:45

Open a file in w+ mode not a+ mode.
Get the length of text to add ($chunkLength)
set a file cursor to the beginning of the file if needed
read $chunkLength bytes from the file
return the cursor to the $chunkLength * $i;
write $prepend
set $prepend a value from step 4

do these steps, while EOF

$handler = fopen('1.txt', 'w+');//1
rewind($handler);//3
$prepend = "I would like to add this text to the beginning of this file";
$chunkLength = strlen($prepend);//2
$i = 0;
do{
    $readData = fread($handler, $chunkLength);//4
    fseek($handler, $i * $chunkLength);//5
    fwrite($handler, $prepend);//6

    $prepend = $readData;//7
    $i++;
}while ($readData);//8

fclose($handler);

0人赞添加讨论(0) 举报

上一页 1 2

Need to write at beginning of file with PHP

采纳回答

编辑标签

举报内容

检举类型

检举原因

检举说明(必填)

打开微信“扫一扫”，打开网页后点击屏幕右上角分享按钮

付费偷看金额在0.1-10元之间