Teach you how to write files in PHP in three minutes?

In the previous article, I brought you "How to read files in PHP? (Sharing Summary) ", which introduces in detail how we should read files. This article will continue to show you how we should create and modify files. I hope it will be helpful to everyone!

Reading files must be no longer difficult for everyone, so let’s take a look at how we should modify the file or create the file and modify it.

file_put_contents writes to a file

First, let’s learn a writing method, file_put_contents(), Its syntax is as follows:

int file_put_contents ( string $文件路径, string $写入数据])

It can write a string to the specified file. If the file does not exist, file_put_contents will create a file and return the length of the written bytes. At the same time, you need to know that if there is content in the specified file, it will overwrite the previous content.

The example is as follows:

<?php
   $a = "好好学习，天天向上；福如东海，寿比南山";
   $b = file_put_contents(&#39;test.txt&#39;, $a);
   if($b){
       echo &#39;写入成功，我们读取看看结果试试：&#39;;
       echo file_get_contents(&#39;test.txt&#39;);
   }else{
       echo &#39;写入失败或者没有权限，注意检查&#39;;
   }
?>

Output result:

Test does not originally exist in my directory. txt, after passing the function, test.txt appeared in my directory, and the content is as follows:

We can see from the above example that it is not difficult to write a file Yes, according to the specified function format, the specified file can be written.

<span style="max-width:90%"><strong>fwrite</strong></span> Write with fopen Input operation

#fwrite() function is used to write a string to the file and returns the number of characters written successfully, otherwise it returns FALSE.

First of all, let’s talk about the grammatical structure of fwrite as follows:

int fwrite ( resource $文件资源变量, string $写入的字符串 [, int 长度])

Next we use fwrite plus w in fopen, write mode to write files. The characteristic, as we mentioned in the previous article, is to open in writing mode, point the file pointer to the file header and cut the file size to zero. If the file does not exist then attempts to create it.

<?php
   $a = &#39;test.txt&#39;;
   $b= fopen($a, "w");
   $c = fwrite($b, &#39;好好学习，天天向上；福如东海，寿比南山&#39;);
   fclose($b);
   print $c .&#39;字节被写入了\n&#39;;
?>

Output result:

test.txt in the directory The content of the file is as follows:

From the above example we can get the following summary:

• The file will be opened and rewritten regardless of whether there is a new one

• The original file content will be overwritten

• If the file does not exist, it will be created

Next, let’s compare the differences between several modes:

• r ---can only be read and cannot be written using fwrite

• r ---Can operate read and write

• w ---Only can write function

• w ---Readable and writable

For example:

Still the above example, put the Replace w with r, the example is as follows:

<?php
   $a = &#39;test.txt&#39;;
   $b= fopen($a, "r");
   $c = fwrite($b, &#39;好好学习，天天向上；&#39;);
   fclose($b);
   print $c .&#39;字节被写入了\n&#39;;
?>

Output result:

Through the example we found that writing in r mode is unsuccessful.

The difference between a mode and w mode

Let’s try the above code and replace r with a. , the example is as follows:

<?php
   $a = &#39;test.txt&#39;;
   $b= fopen($a, "a");
   $c = fwrite($b, &#39;好好学习，天天向上；&#39;);
   fclose($b);
   print $c .&#39;字节被写入了\n&#39;;
?>

Output result:

## The text content of test.txt is as follows:

Through the above example, we found that in a mode, every time it is refreshed, it will be written once more. Each write will append content to the end of the file.

Recommended learning: "PHP Video Tutorial"

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