How can functions like file_get_contents and fread be used to manipulate file content in PHP scripts effectively?

When using functions like file_get_contents and fread in PHP scripts to manipulate file content, it is important to understand how these functions work and how to effectively utilize them. These functions can be used to read the content of a file into a string variable, allowing for manipulation of the content through string functions or regex. Additionally, they can be used to read the file content in chunks, which can be useful for processing large files efficiently.

// Example of using file_get_contents to read a file and manipulate its content
$fileContent = file_get_contents('example.txt');

// Manipulate the file content (e.g. replace a specific string)
$fileContent = str_replace('old_string', 'new_string', $fileContent);

// Write the manipulated content back to the file
file_put_contents('example.txt', $fileContent);