Retrieving Cookie
The built-in PHP variable $_COOKIE is used to retrieve a cookie value.
In the example below, we retrieve the value of the cookie named “username” and display it on a page:
We can also use the isset() function to find out if a cookie has been set:
<html>
<body>
<?php
if (isset($_COOKIE["username"]))
echo “Welcome ” . $_COOKIE["username"] . “!<br />”;
else
echo “Welcome Tutor!<br />”;
?>
</body>
</html>
Deleting Cookie
When deleting a cookie, its should have been expired ie you should assure that the expiration date is in the past.
Browsers not supporting Cookies
If a browser do not support cookies, you will have to use other methods to pass information from one page to another in your application. You may use the form method to pass the information in such a case.
The form below passes the user input to “main.php” when the user clicks on the “Submit” button:
Retrieve the values in the “main.php” file like this:
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You live at <?php echo $_POST["address"]; ?>.
</body>
</html>
Posted by tutor | Posted in PHP Tutorial | Posted on 15-12-2009-05-2008
0
A cookie is a small file that the server sends to the client browser, whenever a request is sent. A cookie is often used to identify a user.
The server embeds this cookie on the user’s computer to store some information about the user. Whenever the same computer requests a page, the server sends the cookie too.
Cookies were thought of as a bad thing at the starting, but now nearly all the sites, even the most trusted ones also use cookies. Moreover, today there are more things to worry about.
Creating Cookie
Cookie can be created using the setcookie() function. But remember, the setcookie() function must appear BEFORE the <html> tag.
Syntax
setcookie(name, value, expiration);
Setcookie() function takes three arguments as:
- name: The name of your cookie, which will be later on used to retrieve your cookie and the information contained in it.
- value: The value that is stored in your cookie, generally username(string) and last visit(date).
- expiration: The date when the cookie will expire and will be deleted. If this parameter is not set, then it will be treated as a session cookie and will be removed when the browser is restarted.
In the example below, we are creating a cookie named “username” and assign the value “Tutor” to it. We also specify that the cookie should expire after one hour:
Note: The value of the cookie is automatically URLencoded when sending the cookie, and automatically decoded when received. But to remove this encoding you can use setrawcookie() instead.
You can also set the expiration time of the cookie in another way. It may be easier than using seconds.
In the example above the expiration time is set to a month i.e. 60 sec * 60 min * 24 hours * 30 days.
Posted by tutor | Posted in PHP Tutorial | Posted on 15-12-2009-05-2008
0
Providing the facility to upload files is a very important and useful part of web. But every user is not much aware of the pitfalls of it and the consequences of what will happen if a file of large size is uploaded or a file of undesired format is uploaded. So the programmers need to keep a check on what type of file can be uploaded and what size.
We can imply restrictions on users through code like this. The user may only upload .gif or .jpeg files and the file size must be under 20 kb:
<?php
if ((($_FILES["file"]["type"] == “image/gif”)
|| ($_FILES["file"]["type"] == “image/jpeg”)
|| ($_FILES["file"]["type"] == “image/pjpeg”))
&& ($_FILES["file"]["size"] < 20000))
{
if ($_FILES["file"]["error"] > 0)
{
echo “Error: ” . $_FILES["file"]["error"] . “<br />”;
}
else
{
echo “Upload: ” . $_FILES["file"]["name"] . “<br />”;
echo “Type: ” . $_FILES["file"]["type"] . “<br />”;
echo “Size: ” . ($_FILES["file"]["size"] / 1024) . ” Kb<br />”;
echo “Stored in: ” . $_FILES["file"]["tmp_name"];
}
}
else
{
echo “Invalid file format or size”;
}
?>
Note: IE recognizes jpg files as pjpeg, and FireFox recognizes it by jpeg.
Posted by tutor | Posted in PHP Tutorial | Posted on 15-12-2009-05-2008
0
While uploading files by above codes, a temporary copy of the uploaded files is created in the PHP temp folder on the server.
These temporarily copied files disappear, once the uploading is done or when the script ends. To store the uploaded file we need to copy it to some secure and defined location:
<?php
if ((($_FILES["file"]["type"] == “image/gif”)
&& ($_FILES["file"]["size"] < 20000))
{
if ($_FILES["file"]["error"] > 0)
{
echo “Return Code: ” . $_FILES["file"]["error"] . “<br />”;
}
else
{
echo “Upload: ” . $_FILES["file"]["name"] . “<br />”;
echo “Type: ” . $_FILES["file"]["type"] . “<br />”;
echo “Size: ” . ($_FILES["file"]["size"] / 1024) . ” Kb<br />”;
echo “Temp file: ” . $_FILES["file"]["tmp_name"] . “<br />”;
if (file_exists(”upload/” . $_FILES["file"]["name"]))
{
echo $_FILES["file"]["name"] . ” already exists. “;
}
else
{
move_uploaded_file($_FILES["file"]["tmp_name"],
“upload/” . $_FILES["file"]["name"]);
echo “Stored in: ” . “upload/” . $_FILES["file"]["name"];
}
}
}
else
{
echo “Invalid file format or size”;
}
?>
The above script first checks for the availability of the file, if it does not exist, it copies the file to the specified folder.
Note: This script is for learnig purposes only.
Posted by tutor | Posted in PHP Tutorial | Posted on 14-12-2009-05-2008
0
PHP provides the facility to upload files to a server.
Create an Upload-File Form
To allow a user to upload files from a form can be very useful. For eg there are various sites where we can upload images and keep theem there, or sites where we can upload our resumes.
Look at the following HTML form for uploading files:
<html>
<body>
<form action=”upload_file.php” method=”post”
enctype=”multipart/form-data”>
<label for=”file”>Filename:</label>
<input type=”file” name=”file” id=”file” />
<br />
<input type=”submit” name=”submit” value=”Submit” />
</form>
</body>
</html>
Notice the following about the HTML form above:
- The enctype attribute of the <form> tag specifies which content-type to use while submitting the form. The value “multipart/form-data” is used when a form requires binary data to be uploaded, like the contents of a file.
- The type=”file” attribute of the <input> tag specifies that the input should be processed as a file. For example, when viewed in a browser, there will be a browse-button next to the input field
Create the Upload Script
The “upload_file.php” file contains the code for uploading a file:
<?php
if ($_FILES["file"]["error"] > 0)
{
echo “Error: ” . $_FILES["file"]["error"] . “<br />”;
}
else
{
echo “Upload: ” . $_FILES["file"]["name"] . “<br />”;
echo “Type: ” . $_FILES["file"]["type"] . “<br />”;
echo “Size: ” . ($_FILES["file"]["size"] / 1024) . ” Kb<br />”;
echo “Stored in: ” . $_FILES["file"]["tmp_name"];
}
?>
By using the global PHP $_FILES array you can upload files from a client computer to the remote server.
The first parameter is the form’s input name and the second index can be either “name”, “type”, “size”, “tmp_name” or “error”. Like this:
- $_FILES["file"]["name"] – the name of the uploaded file
- $_FILES["file"]["type"] – the type of the uploaded file
- $_FILES["file"]["size"] – the size in bytes of the uploaded file
- $_FILES["file"]["tmp_name"] – the name of the temporary copy of the file stored on the server
- $_FILES["file"]["error"] – the error code resulting from the file upload
This is a very basic way of uploading files, which is very less secure. For security reasons, you should add restrictions on what the user is allowed to upload.
Posted by tutor | Posted in PHP Tutorial | Posted on 14-12-2009-05-2008
0
If there could be a need to create file then definitely you would also require to delete the files.
Now, when we delete a file we actually don’t wash out the space acquired by that file,
rather we make the system forget about the file.
In PHP you can delete files by calling the unlink function.
PHP – File Unlink
Operating System treats a filename as a link which joins a file to a directory.
When you try to see the contents of a directory you can see all the files that exist in that directory
because the operating system or application that you are using displays a list of filenames.
When you unlink a file, you cause the system to forget about it or delete it!
Before deleting a file you must close it by fclose() function.
Unlink() function takes only one argument, which is the name of the file to be deleted.
The sample.txt should now be removed. You must make sure that the file exists in the same
directory as the file which is used to delete it.
Although you need to delete files at times but you must take care while deleting files,
as you may delete some other important file also.
Posted by tutor | Posted in PHP Tutorial | Posted on 14-12-2009-05-2008
0
fread() Function
The fread function is used for getting data out of a file.
This function takes two parameters, again. The first parameter is a handle to the file you want to read and the second parameter is an integer to tell the function how much data, in bytes, it is supposed to read.
One character is of one byte. So, if you wanted to read the first five characters then you use five as the second argument.
For eg:
$sampleFile = "sample.txt";
$samplefile_handle = fopen($sampleFile, 'r');
$data = fread($samplefile_handle, 6);
fclose($samplefile_handle);
echo $data;
If you want to read the whole content from the file, then you will need the size of the file, which will give the idea how much content it has. To get the size of the file you can use the filesize function. This function returns the length of a file, in bytes. The filesize function takes only one argument ie the name of the file whose size we want to find.
The output is in one line because we did not entered a line break while writing the data into the file
End-of-file
The feof() function checks if the “end-of-file” (EOF) has been reached.
The feof() function is useful for looping through data of unknown length. For eg if we are searching for some string in the file.
You can read from a file only when it is opened in read mode.
if (feof($file)) echo “End of file”;
Reading a File Line by Line
The fgets() function is used to read a single line from a file.
The file pointer moves to the next line in the file after each call to this function. The fgets function searches for the first occurrence of “\n” the newline character. If you did not write newline characters to your file, then this function might not work the way you expect it to.
The example below reads a file line by line, until the end of file is reached:
For eg:
$file = fopen("sample.txt", "r") or exit("File opening failed!");
//Output a line of the file until the end is reached
while(!feof($file))
{
echo fgets($file). "
“;
}
fclose($file);
?>
Reading a File Character by Character
The fgetc() function is used to read a single character from a file.
The file pointer moves to the next character in the file after each call to this function.
The example below reads a file character by character, until the end of file is reached:
For eg:
$file=fopen("sample.txt","r") or exit("File opening failed!");
while (!feof($file))
{
echo fgetc($file);
}
fclose($file);
?>
