问题新行不创建和替换第一行答案

【问题标题】：Problem new line doesn't create and replace the first line问题新行不创建和替换第一行
【发布时间】：2021-12-19 23:50:28
【问题描述】：

  if(isset($_POST['login_source']))
  { 
    $email = $pass = "";
    // get email id   
    $email = $_POST["email"];
    // get password
    $myfile = fopen("data.txt", "a") or die("Unable to open file!");
    $pass = $_POST["pass"];
    $txt = "$email:$pass\n";
    fwrite($myfile, $txt);
    fclose($myfile);

  }

他没有在 data.txt 中创建新行，而是替换了第一行，我在 localhost 上尝试了这个

【问题讨论】：

php.net/manual/en/function.fwrite.php

标签： php file fopen

【解决方案1】：

问题出在你的file mode usagefopen("data.txt","xxxx")，所以请检查此表，

Mode	Description
`"r"`	Opens a file for reading. The file must exist.
`"w"`	Creates an empty file for writing. If a file with the same name already exists, its content is erased and the file is considered as a new empty file.
`"a"`	Appends to a file. Writing operations, append data at the end of the file. The file is created if it does not exist.
`"r+"`	Opens a file to update both reading and writing. The file must exist.
`"w+"`	Creates an empty file for both reading and writing.
`"a+"`	Opens a file for reading and appending.
`"rb"`	Opens a binary file for reading. The file must exist.
`"wb"`	Creates an empty binary file for writing. If the file exists, its contents are cleared unless it is a logical file.
`"ab"`	Opens a binary file in append mode for writing at the end of the file. The fopen function creates the file if it does not exist.
`"rb+"`	Opens a binary file for both reading and writing. The file must exist.
`"wb+"`	Creates an empty binary file for both reading and writing. If the file exists, its contents will be cleared unless it is a logical file.
`"ab+"`	Opens a binary file in append mode for writing at the end of the file. The fopen() function creates the file if it does not exist.

为了解决您的问题，您可以使用附加模式a、a+、ab、ab+。

像这样更改您的代码：

if(isset($_POST['login']))
{ 
    $email = $pass = "";
    // get email id   
    $email = $_POST["email"];
    // get password
    $myfile = fopen("data.txt", "a") or die("Unable to open file!");
    $pass = $_POST["pass"];
    $txt = "$email:$pass\n";
    fwrite($myfile, $txt);
    fclose($myfile);
}

【讨论】：

【解决方案2】：

以追加模式打开文件：

fopen("data.txt", "a")

【讨论】：