php creates and modifies file content

In the previous section we learned that reading files is particularly easy to master. In this section we will explain writing to files.

file_put_contentsWrite file

---

##Let’s first learn the first way to write a file:

int file_put_contents (string $file path, string $write data])

Function: Write a string to the specified file, and create the file if it does not exist. What is returned is the length of written bytes

<?php
   $data = "在PHP中文网学好PHP，妹子票子不再话下！";

   $numbytes = file_put_contents('binggege.txt', $data);

   if($numbytes){

       echo '写入成功，我们读取看看结果试试：';

       echo file_get_contents('binggege.txt');

   }else{
       echo '写入失败或者没有权限，注意检查';
   }
?>

We found that writing files is quite simple. According to the format of this function, specify the file and write the string data.

fwrite cooperates with fopen to perform write operations

---

##int fwrite (resource $file resource variable, string $written string [, int length])

Note: The alias function of fwrite is fputs

We tried r mode in the last class, which was only used when reading. Next, we use fwrite plus w in fopen to write files in write mode.

Let’s take a look at the features:

Open the 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.

Note: In the following experiment, you can try to create a new test.txt file and write content into it. Then, you can try to delete test.txt. See what tips there are.

<?php
   $filename = 'test.txt';
   $fp= fopen($filename, "w");
   $len = fwrite($fp, '我是一只来自北方的狼，却在南方冻成了狗');
   fclose($fp);
   print $len .'字节被写入了\n';
?>

Summary:

1. Regardless of whether there is a new file, the file will be opened and rewritten

2. The original file content will be overwritten
3. If the file does not exist, it will be created

Let’s compare the differences between the following modes:

Moderr+ww+

Let’s prove it through experiments:

<?php
   $filename = 'test.txt';
   $fp= fopen($filename, "r+");
   $len = fwrite($fp, '我是一只来自南方的狼，一直在寻找心中的花姑娘');
   fclose($fp);
   print $len .'字节被写入了\n';
?>

You can remove the + sign after r during the experiment.

Through experiments, we have indeed found that using r mode, data can be written when the file is saved. If only r is used, the writing is unsuccessful.

The difference between a mode and w mode

The same is the code below, we change it to a mode.

<?php
   $filename = 'test.txt';
   $fp= fopen($filename, "a");
   $len = fwrite($fp,'读大学迷茫了，PHP中文网学PHP给你希望');
   echo  $len .'字节被写入了\n';
?>

Open the webpage and execute this code, you will find: every time you refresh, there will be an extra paragraph in the file
: If you are confused in college, learning PHP on the Chinese PHP website will give you hope.

Summary:

Description
Can only be read and cannot be written using fwrite
Can be read and written
Only write function
Readable and writeable

Mode	Summary
x	Every time you write, the contents of the original file will be deleted. If the file does not exist, it will be created.
a	Every time you write, it will be written to the end of the file. Additional content

# Note: a+ is an enhanced additional function. It can also be used when it can be read.

The difference between x mode and w mode

Let’s try this code again and change it to x mode:

<?php
   $filename = 'test.txt';
   $fp= fopen($filename, "x");
   $len = fwrite($fp,'读大学迷茫了，PHP中文网学PHP给你希望');
   echo  $len .'字节被写入了\n';
?>

We will find:

1 . An error will be reported when the file exists

2. If you change $filename to another file name, it will be fine. However, when refreshing again, an error was reported

3.x+ is an enhanced x mode. Can also be used when reading.

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