What is the function to modify files in php

Modify function: 1. fwrite(), you can write a string to a file, the syntax is "fwrite(specify file, write data, number of bytes written)"; 2. file_put_contents( ), syntax "file_put_contents(file name, written data, writing mode)".

The operating environment of this tutorial: windows7 system, PHP version 8.1, DELL G3 computer

There are two functions in php to modify files: fwrite () and file_put_contents() function

1, fwrite() function

fwrite() function can write a string to a file, the syntax format of the function As follows:

fwrite(resource $handle, string $string[, int $length])

The parameter description is as follows:

• $handle: The file to be written is the resource created by fopen();

• $string: The string to be written;

• $length: Optional parameter, used to set the number of bytes to be written.

The fwrite() function can write the contents of $string to the file pointer $handle. If $length is specified, writing will stop when $length bytes have been written or $string has been written. If the function is successfully executed, the number of bytes written will be returned. If the function fails, FALSE will be returned.

Example: There is a text file named "test.txt", the content is:

##

<?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 File

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:

As you can see, we clear the file and re-add the data.

2. file_put_contents() function

file_put_contents() function has the same function as fwrite() function. It can also write a string to a file. The syntax format As follows:

file_put_contents(string $filename, mixed $data[, int $flags = 0[, resource $context]])

Parameter description is as follows:

$filename: The name of the file to which data is to be written;
$data: The data to be written can be a string, one-dimensional array or resource type;
$flags: Optional parameter, its value can be the following (can be used in combination with the
• | operator):
              FILE_USE_INCLUDE_PATH: Search for $filename in the include directory.
              FILE_APPEND: If file $filename already exists, append data instead of overwriting.
              LOCK_EX: Obtain an exclusive lock while writing.
$context: Optional parameter, a context resource.

Same as the fwrite() function. The file_put_contents() function will return the number of bytes of data written to the file if executed successfully. If failed, it will return a Boolean value of FALSE or a non-Boolean value equivalent to FALSE.

Example 1: Clear the file and re-add the data

<?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 see Look at the content:

Example 2: Append writing data at the end of the file

<?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 look at the content:

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