fopen ( ) is a system function available in PHP.

Main objective of PHP and HTML form controls are to collect data from users.

Forms and files are most important concepts that the PHP web development processes.

The following control are available in HTML forms:
(i) Text inputs
(ii) Buttons
(iii) Checkbox
(iv) Radio box
(v) File Select
(vi) Form Tag

HTML form controls are used to collect data from user.

Validation rules for HTML input field:

< html >
< head >
< title > Login Form < /title >
< body >
< h3 align=center > TamiiNadu State Council of
EducationalResearchand Training, Chennai < /h3 >
< Form Action = "mailto:abcd.xyz@com"
method =post >
< p > User Name:
OUTPUT:
< Input type = text name="user_name" size = 20 maxlength = 15 > < /p >
< p > Password:
< Input type = password name="pass" size = 20 maxlength = 15 > < /p >
< Input type = reset value = "Clear" >
< Input type = submit value = "Login" >
< /Form >
< /body >
< /html >

i) Text(Notepad) file:
AJAX = Asynchronous JavaScript and XML
CSS = Cascading Style Sheets
HTML = Hyper Text Markup Language
PHP = PHP Hypertext: Preprocessor
SQL = Structured Query Language
SVG = Scalable Vector Graphics
XML = EXtensible Markup Language
ii) PHP File:
< ?php
＄myfile = fopen("webdictionary.txt", "r'') or
die("Unable to open file!'');
echo fread( ＄myfile, filesize("webdictionary.
txt'')); fclose(＄myfile);
? >
iii) OUTPUT 
AJAX = Asynchronous JavaScript and XML
CSS = Cascading Style Sheets
HTML = Hyper Text Markup Language
PHP = PHP Hypertext Preprocessor
SQL = Structured Query Language
SVG = Scalable Vector Graphics
XML = EXtensible Markup Language

The GET and POST methods are used for sending the data to the server and the main difference between them is that GET methods append the data to the URI defined in form's action attribute POST methods attaches data to the requested body.

(i) To get form data, we need to use PHP $_GET and S_POST.
(ii) To retrieve data from get request, we need to use $_GET and for post request $_POST.
(iii) We can send limited amount of data through get request and large amount of data through post request.

1. File upload is the best feature to select one file from the local machine to server machine.
2. Form tag is used to mention a method as POST or GET and encrypt attribute mentioned as "multipart/form-data".
3. In the < Input > tag mention type="file" attribute shows the input field as a file-select control, with a "Browse" button next to the input control.
4. The form above sends data to a file.
5. In Server machine "php.ini" file, search for the file_uploads directive, and set it to On: "file_uploads = On"
6. After submitting the upload button the request reaches to the file.
7. In the file ＄FILES variable collects all uploaded file information such as name of the file, size of the file and extension of the file etc.
8. All the details are checked thoroughly and the errors are saved in an array variable.
9. The file finally moves under the image directory if the array error variable is empty.

File handling is an important activity of all web application development process.
Files are processed for different tasks using the following events :
(i) PHP Open a File,
(ii) PHP Read a File,
(iii) PHP Close a File,
(iv) PHP Write a File,
(v) PHP Appending a File and 
(vi) PHP uploading a File.
(1) PHP Open a File : fopen() is a system function available in PHP. This function helps to open a file in the server. It contains two parameters one for the file and the other one specifies in which mode the file should be opened (Read/Write).
Syntax:
$file_Object= fopen("FileName", "Read/
WriteMode") or die("Error Message!");
Example:

$myfile = fopen("Student.txt", "r")
or die("Unable to open file!");
?>
(ii) PHP Read a File: The fread() function reads from an open file. The file object comes from fopen function.
Syntax:
fread($file_Object,filesize("FileName"));
Example:

fread($myfile,filesize("Student.txt"));
?>
(iii) PHP Close a File: The fclose() function is used to close an opened file. The file object comes from fopen function.
Syntax:
fclose($file_Object);
Example:

(iv) PHP write a File: The fwrite() function is used to write to a file.
Syntax: