A complete list of essential file processing functions for PHP development

PHP is a high-level programming language widely used in website development and back-end services. As developers, we need to handle a large number of files, such as reading and writing files, creating directories, deleting files, etc. In this article, we will introduce you to some common operations and techniques of PHP file processing functions to help developers better process files.

1. File processing function

1. fopen(): Open the file and return a file pointer, which can be used to read or write the file.
2. fclose(): Close an open file pointer.
3. fread(): Read data from the open file and return the content.
4. fwrite(): Write data to the open file.
5. fgets(): Read one line of data from the open file each time and return the content.
6. fgetcsv(): Read data from the open file and parse it into an array in CSV format.
7. file_get_contents(): Try to read the entire file and return the contents.
8. file_put_contents(): Write the given data to the file.
9. rename(): Rename the file or move the file to a new location.
10. unlink(): Delete the specified file.
11. copy(): Copy the file.
12. filesize(): Returns the size of the file.
13. is_file(): Check whether the given path is a file.
14. is_dir(): Check whether the given path is a directory.

2. File reading and writing

In PHP, file reading and writing are very common operations. We can use the fopen() function to open a file pointer, then use fread() to read the content from the file, and use fwrite() to write the content to the file.

1. Read the contents of the file

$file = fopen("test.txt", "r") or die("Unable to open file!");
echo fread($file, filesize("test.txt"));
fclose($file);
?>

Here, We opened a file named test.txt and read the contents of the file using the fread() function. Finally, we close the file using the fclose() function.

2. Write data to the file

$file = fopen("test.txt", "w") or die(" Unable to open file!");
$txt = "Hello world
";
fwrite($file, $txt);
$txt = "How are you today?
" ;
fwrite($file, $txt);
fclose($file);
?>

Here, we use the fopen() function to create a file named test .txt file, and use the fwrite() function to write the content to the file. Finally we close the file via fclose().

3. File upload

File upload is also a very common PHP operation. We can use the $_FILES array to get the data from the uploaded file and use the move_uploaded_file() function to move the file to the target directory on the server.

1. Get uploaded files

print_r($_FILES);
?>

Here, We can use the print_r() function to print the contents of the uploaded file.

2. Move the file to the target directory

$target_dir = "uploads/";
$target_file = $target_dir . basename( $_FILES"fileToUpload");
if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
echo "The file ". htmlspecialchars( basename( $_FILES"fileToUpload" )). " has been uploaded.";
} else {
echo "Sorry, there was an error uploading your file.";
}
?>

在Here, we first set the target directory for uploading files and generate a target path $target_file. We then use the move_uploaded_file() function to move the uploaded file into the target directory.

4. Directory processing

In PHP, you can also handle operations such as creating, opening, moving and deleting directories.

1. Create directory

if (!file_exists('directory_name')) {

mkdir('directory_name', 0777, true);

}
? >

Here, we use the mkdir() function to create a directory named directory_name. If the directory does not exist, create it.

2. Open a directory

$dir = "/folder/";
// Open a directory, and read its contents
if (is_dir($dir)){
if ($dh = opendir($dir)){

while (($file = readdir($dh)) !== false){
  echo "filename:" . $file . "<br>";
}
closedir($dh);

}
}
?>

Here, we have opened a directory using the function opendir(), traversed its contents using the function readdir(), and closed a directory using the function closedir().

3. Delete the directory and its contents

function deleteDirectory($dir) {

if (!file_exists($dir)) {
    return true;
}

if (!is_dir($dir)) {
    return unlink($dir);
}

foreach (scandir($dir) as $item) {
    if ($item == '.' || $item == '..') {
        continue;
    }

    if (!deleteDirectory($dir . DIRECTORY_SEPARATOR . $item)) {
        return false;
    }

}

return rmdir($dir);

}

?>

Here, we define a function deleteDirectory(), which uses recursion to delete all subdirectories and files including directories.

Summary

In this article, we introduced some basic operations of PHP file processing functions, including file reading and writing, file uploading and directory processing. Of course, these functions are not only part of PHP's file processing work, they also cover many other aspects of PHP programming. When you use these functions, make sure you understand and master how to manipulate files and directories.

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