PHP file operation: how to clear the file and re-add data

In the previous article, we introduced the method of reading all the data of the file at one time. If you are interested, you can click on the link to read "php file operation: How to obtain all the data of the file at one time". We have learned a lot about file reading operations. Let’s take a look at file writing operations.

As the title says, today’s topic is to introduce overwriting (clearing the original content of the file and then re-adding the data). Below we will give you a detailed introduction through code examples.

Still with the previous example, there is a text file named "test.txt", the content of which is:

I want to change "test. txt" file content is changed to:

HELLO PHP!

Let’s take a look at the implementation code:

<?php
header("Content-Type: text/html;charset=utf-8");    //设置字符编码
$file = "test.txt";
$handle = fopen($file, &#39;w&#39;);                 //打开文件
fwrite($handle, &#39;HELLO PHP!&#39;);    //写入内容
fclose($handle);//关闭文件
?>

After writing the content, we read the file and see if it is overwritten.

readfile($file);   //读取并输出文件全部内容

Look at the output result:

Re-open the "test.txt" file and look at the content:

Write successfully! Let’s take a look at the key statements:

fopen($file, 'w') Statement: The fopen() function can open a file according to the specified file mode $mode ;When $mode is w or w , the contents of the file will be cleared while opening the file.

fwrite($handle, 'HELLO PHP!')Statement: Write the string "HELLO PHP!" to the open file.

In addition to using the fopen and fwrite() functions to overwrite and write, we can also directly use the file_put_contents() function to clear the original content of the file and re-add data.

Look at the following example:

<?php
header("Content-Type: text/html;charset=utf-8");    //设置字符编码
$file = "test.txt";
file_put_contents($file, &#39;欢迎来到PHP中文网！&#39;);    //写入内容
readfile($file);   //读取并输出文件全部内容
?>

The output result is:

Reopen the "test.txt" file and look at the content ：

Let’s take a look at the file_put_contents() function:

file_put_contents($filename,$data,$mode,$context)The function can write a string into a file and accepts two required parameters $filename (the file to be opened) and $data (the content to be inserted, which can be a string , one-dimensional array or resource type), two omitted parameters $mode and $context (the environment of the file handle).

Among them, the $mode parameter is used for how to open/write files (i.e. file mode), and has three values:

• FILE_USE_INCLUDE_PATH: Default value, used to overwrite the original data.

• FILE_APPEND: If file $filename already exists, append data instead of overwriting.

• LOCK_EX: Obtain an exclusive lock while writing.

<?php
header("Content-Type: text/html;charset=utf-8");    //设置字符编码
$file = "test.txt";
file_put_contents($file, &#39;欢迎来到PHP中文网！33&#39;,FILE_APPEND|LOCK_EX);    //写入内容
readfile($file);   //读取并输出文件全部内容
?>

Reopen the "test.txt" file and take a look at the content:

As you can see, we are at the end of the file A new piece of data has been added! Therefore, the file_put_contents() function can not only be used to overwrite and write , but also append to write .

Okay, that’s all. If you want to know anything else, you can click this. → →Basic operation of PHP files

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