PHP File Operation Tips: Efficient Methods for Reading and Writing Files

1. PHP File Reading Tips

In PHP, there are two common ways to read file content: using the file_get_contents() function to read the entire file or combining the fread() and fopen() functions to read file content as needed. Here's an example of reading a file with file_get_contents():

$filename = "example.txt";
$content = file_get_contents($filename);
echo $content;

For reading larger files, it's recommended to use a combination of the fread() and fopen() functions. Here is an example:

$filename = "example.txt";
$handle = fopen($filename, "r");
$content = "";
$length = 1024; // Read 1024 bytes at a time
while (!feof($handle)) {
    $content .= fread($handle, $length);
}
fclose($handle);
echo $content;

1.1 file_get_contents() Function

The file_get_contents() function is used to read an entire file's content into a string in PHP. Below is the basic syntax of the file_get_contents() function:

$content = file_get_contents($filename);

Here, $filename is the file path. If successful, it returns the file content as a string; if it fails, it returns FALSE. It's important to note that file_get_contents() loads the entire file into memory, which may lead to high memory usage if the file is large.

1.2 fopen() and fread() Functions

The fopen() function is used to open a file, while fread() is used to read its contents. Below is the basic usage of these functions:

$handle = fopen($filename, $mode);
$content = fread($handle, $length);

During this process, $filename is the file path, and $mode is the file opening mode. Common modes include:

• "r": Read-only mode, with the file pointer at the beginning of the file.
• "w": Write-only mode, with the file pointer at the beginning and the file contents cleared.
• "a": Append mode, with the file pointer at the end of the file. If the file doesn't exist, it will be created.
• "x": Exclusive lock mode, which creates the file if it doesn't exist.

It's important to control the length of data read using fread(), especially when working with large files, to avoid memory overflow.

2. PHP File Writing Tips

In PHP, you can use the file_put_contents() function to write content to a file or combine fwrite() and fopen() functions for writing content in chunks. Here is an example of using file_put_contents() to write to a file:

$filename = "example.txt";
$content = "hello world";
file_put_contents($filename, $content);

For writing large files, it's better to use a combination of fwrite() and fopen(). Here is an example:

$filename = "example.txt";
$handle = fopen($filename, "w");
$content = "hello world";
fwrite($handle, $content);
fclose($handle);

2.1 file_put_contents() Function

The file_put_contents() function is a simple way to write content to a file in PHP. Below is the basic syntax for file_put_contents():

file_put_contents($filename, $content);

Here, $filename is the file path, and $content is the content to be written. This method is suitable for writing smaller files, but for larger files, special care should be taken regarding memory usage.

2.2 fopen() and fwrite() Functions

The fopen() function is used to open a file, and fwrite() is used to write content to the file. Below is the basic usage of these functions:

$handle = fopen($filename, $mode);
$result = fwrite($handle, $content);
fclose($handle);

Here, $filename is the file path, $mode is the file opening mode, and $content is the data to be written. The fwrite() function returns the number of bytes successfully written, or FALSE if it fails.

Similar to reading, when writing large files, it's important to control the length of data written to avoid memory overflow.