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5. Other functions of PHP_PHP tutorial
- WBOYOriginal
- 2016-07-21 16:08:48733browse
5. Other miscellaneous items
5.1 Generate images
PHP can operate and process images. If you have the GD library installed, you can even generate images using PHP.
Header("Content-type: image/gif");
$string=implode($argv," ");
$im = imagecreatefromgif("images/button1.gif");
$orange = ImageColorAllocate($im, 220, 210, 60);
$px = (imagesx($ im)-7.5*strlen($string))/2;
ImageString($im,3,$px,9,$string,$orange);
ImageGif($im) ;
ImageDestroy($im);
?>
(Translator’s Note: The above code segment lacks comments, please refer to the image processing function section of PHP Manual)
This code is called in other pages through the following tag , and then the above button.php3 code obtains the text value and obtains the image in another Add this value to the file--in the above code, the image file is images/button1.gif--and finally output it to the browser. If you want to use an image button in a form field, but don't want to have to regenerate a new image every time the text on the button changes, you can use this simple method to dynamically generate an image file.
5.2 Cookies
PHP supports HTTP-based cookies. When needed, you can use cookies just as easily as regular variables. Cookies are pieces of information that the browser saves on the client, so you can know whether anyone on a specific PC has visited your site, the visitor's traces on your site, and so on. A typical example of using cookies is the screening of browser preferences. Cookies are set by the function setcookie(). Like the function header() that outputs HTTP headers, setcookie() must be called before any actual content is output to the browser. The following is a simple example:
if (empty($VisitedBefore))
{
// If no cookie is set, Assign the current time value to the cookie
// The last parameter in the function declares the time the cookie is saved
// In this example it is 1 year
/ / The time() function returns the time in seconds since January 1, 1970
SetCookie("VisitedBefore",time(), time()+(60*60*24*365) );
}
else
{
// Visitors are welcome to come again
echo "Hello there, welcome back< BR>";
// Read the cookie and determine
if ( (time() - $VisitedBefore) >= "(60*60*24*7)" )
echo "Why did you take a week to come back. You should be here more often!?
";
}
?>
5.3 HTTP-based authentication
HTTP-based authentication cannot be implemented when PHP is running in CGI mode. We can use the function header() to send an HTTP header to force authentication, and the client browser will pop up a dialog box for entering the username and password. These two variables are stored in $PHP_AUTH_USER and $PHP_AUTH_PW. You can use these two variables to verify legality and allow entry. The following example authenticates a user's login for tnc/nature using a username/password pair:
if(!isset($PHP_AUTH_USER))
{
Header("WWW-Authenticate: Basic realm="My Realm"");
Header("HTTP/1.0 401 Unauthorized");
echo " Text to send if user hits Cancel buttonn";
exit;
}
else
{
if ( !($ PHP_AUTH_USER=="tnc" && $PHP_AUTH_PW=="nature")
)
{
// If it is a wrong username/password pair, force re-authentication
Header("WWW-Authenticate: Basic realm="My Realm"");
Header("HTTP/1.0 401 Unauthorized");
echo "ERROR : $PHP_AUTH_USER/ $PHP_AUTH_PW is invalid.";
exit;
}
else
{
echo "Welcome tnc!";
}
?>
In fact, in actual references, it is unlikely to use the obvious user name/password pair in the code snippet above, but instead uses a database or encrypted Password files to access them.
5.4 File Upload
You can use PHP to implement the file function. Note that the client browser should be Netscape3 or above or IE3 or above.以下就是该功能的简单演示：
( upload.html ):
ENCTYPE="multipart/form-data" METHOD=POST>
NAME="MAX_FILE_SIZE" VALUE="2000000">
NAME="uploadfile" SIZE="24" MAXLENGTH="80">
NAME="sendit">
NAME="cancelit">
delay while we upload your file.)
下面是处理上传的文件：
( receiver.php3 ):
function do_upload ()
{
global $uploadfile, $uploadfile_size;
global $local_file, $error_msg;
if ( $uploadfile == "none" )
{
$error_msg = "You did not specify a file for uploading.";
return;
}
if ( $uploadfile_size > 2000000 )
{
$error_msg = "Sorry, your file is too large.";
return;
}
$the_time = time ();
// 你需要对以下目录有写权限
$upload_dir = "/local/uploads";
$local_file = "$upload_dir/$the_time";
if ( file_exists ( '$local_file' ) )
{
$seq = 1;
while ( file_exists ( "$upload_dir/$the_time$seq" ) ) { $seq++; }
$local_file = "$upload_dir/$the_time$seq";
};
rename ( $uploadfile, $local_file );
display_page ();
}
function display_page ()
{
// 这里是你的页面内容
}
if ( $error_msg ) { echo "$error_msg
";
}
if ( $sendit )
{
do_upload ();
}
elseif ( $cancelit )
{
header ( "Location: $some_other_script" );
exit;
}
else
{
some_other_func ();
}
?>
5.5 常用函数
我们简单来看看一些常用的函数。
Array
array - generate array
count - number of array elements
sort - Array sorting, there are several other sorting functions available
list - List array elements
each - Return the next key/value pair
current - Returns the current array element
next,prev - Returns the pointers before and after the current array element
Date and Time
checkdate - Verify date/time format
date - Generate date/time format
time - Current time information
strftime - Format date/time
Directory, file system
chdir - Change directory
dir - Directory category
opendir, readdir, closedir - open, read, close the directory
fopen, fclose - open, close the file
fgets, fgetss - read the content line by line
file - Read the entire file into an array variable
Regular expression
ereg - Match regular expression
eregi - Matches regular expressions in case insensitive
ereg_replace - Matches regular expressions and replaces them
eregi_replace - Matches regular expressions in case insensitive cases and replaces them
split - Split the string according to the rules and store it in array form
String
AddSlashes - Use a string after adding a slash
echo - Output one or more strings
join, implode - Combine array elements into a string
htmlentities, htmlspecialchars - Convert HTML special characters into HTML tag form
split - Split the string according to rules and store it in array form
5.6 Extend our sample homepage
We will use some of the functions and ideas mentioned above to add more dynamic content to our sample homepage. We can add a navigation bar at the top of each page, and at the same time make the current page automatically not displayed by links; we can also add a user verification form to upload music, images and other files and automatically update the page.
Navigation bar
is actually adding a piece of code to the footer.inc file. Assuming that all files with the suffix .php3 in your website will appear in the navigation bar, the following is the code saved as include/navbar.inc:
/* Output the navigation bar and link all .php3 files in the site except the current page */
# Read directory
$d = dir("./");
echo "
| n";
while($entry = $d->read())
{
/ / Ignore no file condition
if ( !is_file($entry) )
continue;
/* Separate the file name from the extension. Since . is a special character in regular expressions, it should be introduced */
list($filenm, $fileext) = split(".",$entry, 2);
// Ignore Non-.php3 files
if( $fileext != "php3" )
continue;
/* Now that we have selected all the .php3 files, let’s search The first line (title) in the file
is similar to $title="something";
and separate the above title content as link text */
$linknm = "";
$fp=fopen($entry,"r");
while($buffer=fgets($fp, 4096))
{
$buffer = trim($buffer);
// We have put the title of each file on the first line of the file for easy search
// But when you Changing variable names may cause trouble
if (ereg("title *= *"", $buffer))
{
/* We have obtained The title content can be removed based on
.
must be processed in PHP code, such as $title = "blah blah" */
. eval($buffer);
// Then display the link text as title text
$linknm = $title;
break;
}
}
fclose($fp);
if ( $entry == basename($PHP_SELF) )
echo "$linknm";
else
echo "$linknm";
echo " | ";
}
$d->close();
echo "
?>
Photo Collection
We will refer to HTTP-based authentication, file system functions and file upload functions to maintain the directory where the image files are placed.
At the same time, we need to create a directory. A page that lists all photos in this directory.
File upload
include("include/common.inc");
// We are here Do another user verification here
if(!isset($PHP_AUTH_USER))
{
Header("WWW-Authenticate: Basic realm="$MySiteName"") ;
Header("HTTP/1.0 401 Unauthorized");
echo "Sorry, you are not authorized to upload filesn";
exit;
}
else
{
if ( !($PHP_AUTH_USER==$MyName && $PHP_AUTH_PW==$MyPassword ) )
{
// If it is a wrong username/password pair, force re-authentication
Header("WWW-Authenticate: Basic realm="My Realm"");
Header( "HTTP/1.0 401 Unauthorized");
echo "ERROR : $PHP_AUTH_USER/$PHP_AUTH_PW is invalid.
";
exit;
}
}
if ( $cancelit )
{
// When the visitor presses the "Cancel" button, it will redirect to the homepage
header ( "Location: front_2.php3" );
exit;
}
function do_upload () {
global $userfile, $userfile_size, $userfile_name, $userfile_type;
global $local_file, $error_msg;
global $HTTP_REFERER;
if ( $userfile == "none" ) {
$error_msg = "You did not specify a file for uploading.";
return;
}
if ( $userfile_size > 2000000 )
{
$error_msg = "Sorry, your file is too large.";
return;
}
// Wherever you have write permission below...
$upload_dir = "photos";
$local_file = "$upload_dir/$userfile_name";
if ( file_exists ( $local_file ) ) {
$error_msg = "Sorry, a file with that name already exists";
return;
};
// You can also use this Check file name/type pairs to determine what kind of file it is: gif, jpg, mp3...
rename($userfile, $local_file);
echo "The file is uploaded
n ";
echo "Go Back
n";
}
$title = "Upload File";
include("include/header.inc");
if (empty($userfile)
$userfile=="none")
{
// Output the following form
?>
(You may notice a slight delay while
we upload your file.)< ;/I>
} else {
if ( $error_msg ) { echo "$error_msg
";
}
if ( $sendit ) {
do_upload ();
}
}
include("include/footer.inc");
?>
Photo Gallery
include("include/common.inc");
$title = "Gallery";
include("include/header. inc");
?>
Here are some of our family photos. This PHP script can really
be made better, by splitting into multiple pages. while($entry = $d->read())
{
if (is_file("photos/$entry"))
echo "n";
}
$d->close();
?>
include("include/footer.inc");
?>
Also, you can upload the file in the file upload form Add an input element to describe the uploaded file. This element will be stored in the file and then read and displayed by the code in the photo gallery above.