Use php to create verification code technology

This function is a string required to generate a verification code. Principle: First, we integrate letters and numbers, then use the str_shuffle function to disrupt the string, and then extract the required length to return .? Php ** function Description: This function returns different types or strings of different lengths to create a verification code *** function

This function is a string required to generate a verification code. Principle: first integrate letters and numbers, then use the str_shuffle function to disrupt the string, and then extract the required length to return. ? Php/** function Description: This function is used to return different types or strings of different lengths for verification code ***/function

This function is a string required to generate a verification code. Principle: first integrate letters and numbers, then use the str_shuffle function to disrupt the string, and then extract the required length to return.

/*
* Function Description: This function returns different types or strings of different lengths to create verification codes.
*
**/
Function buildRandomString ($ type = 1, $ length = 4)
{
If ($ type = 1)
{
// Pure numeric verification code. join converts the array to the meaning of the range distribution of the string.
$ Chars = join ("", range (0, 9 ));
}
Else if ($ type = 2)
{
// Array_merge () combines several arrays into one
$ Chars = join ("", array_merge (range ("a", "z", range ("A", "Z "))));
}
Else if ($ type = 3)
{
$ Chars = join ("", array_merge (range ("a", "z", range ("A", "Z"), range (0, 9 ))));
}
If ($ length> strlen ($ chars ))
{
Exit ("too long ");
}
// Disrupt the string Function
$ Chars = str_shuffle ($ chars );
Return substr ($ chars, 0, $ length );
}

?>

The part used to create the verification code

// Create a canvas
Require_once 'string. func. php ';
Header ("Content-type: image/png ");
$ Width = 180;
$ Height = 28;
// Set the color
$ Image = imagecreatetruecolor ($ width, $ height );
$ White = imagcolorallocate ($ image, 255,255,255 );
$ Black = imagecolorallocate ($ image, 0, 0 );
Imagefilledrectangle ($ image, 1,1, $ width-2, $ height-2, $ black );
// ImageFill ($ image, 0, 0, $ white );
// ImageLine ($ image, 10, 10, 90, 40, $ black );
// The type is 1 and the length is 8
$ Type = 1;
$ Length = 8;
// Set the verification code based on the type and length
$ Chars = buildRandomString ($ type, $ length );
$ Sess_name = "verify ";
$ _ SESSION [$ sess_name] = $ chars;
// Create the font file required for the verification code
$ Fontfiles = array ("MSYH. TTF "," MSYHBD. TTF "," SIMFANG. TTF "," SIMHEI. TTF "," SIMKAI. TTF "," SIMSUN. TTC ");
For ($ I = 0; $ I <$ length; $ I ++)
{
// You can specify the size, angle, and font type.
$ Size = mt_rand (14,18 );
$ Angle = mt_rand (-15, 15 );
$ X = 5 + $ I * $ size;
$ Y = mt_rand (20, 26 );
$ Fontfile = "../fonts/". $ fontfiles [mt_rand (0, count ($ fontfiles)-1)];
$ Color = imagecolorallocate ($ image, mt_rand (50, 90), mt_rand (80,200), mt_rand (90,100 ));
$ Text = substr ($ chars, $ I, 1 );
Imagettftext ($ image, $ size, $ angle, $ x, $ y, $ color, $ fontfile, $ text );
}
Imagepng ($ image );
// Remember to release the resource
ImageDestroy ($ image );
?>

The final result shows the type and font verification code of the required length.