Verification code is a common feature in WEB2.0 now, such as registration, login or Message page, you need a registration code to verify the legitimacy of the current operator, we will see some sites do not have verification code, but that is more advanced verification, the following we look at the common code generation and use method.
11 Simple Verification Code examples
1.1 Picture showing the verification code
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$num =intval (Mt_rand (1000,9999));
for ($i =0; $i <4; $i + +)
{echo "";}
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1.2 Verification process
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if (Strval ($INPUTYZM)!=strval ($num))
{
echo "";
Exit
} |
Example of verification code for 21 characters
2.1 Picture showing the verification code
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$str = "Han", "word", "test", "certificate", "code"); Can define the content and number of Chinese characters
$word =strlen ($STR));
for ($i =0; $i <4; $i + +)
{
$num =rand (0, $word);
$img = $img. "";
$pic = $pic. $str [$num];
}
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2.2 Assign the generated random string to a hidden field
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2.3 Define a check () function
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See a complete example
PHP Verification code generation and invocation of the example, usually in the development of often used, record a bit.
1. Verification code Generation file code.php
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!--?
Header ("Content-type:image/png");
//define header, declare picture file, preferably PNG, no copyright disturbance;
//Generate a new four-bit integer verification Code
Session_Start ();//open session;
Authnum_session = ";
str = ' abcdefghijkmnpqrstuvwxyz1234567890 ';
//define the numbers and letters used to display on the image;
L = strlen (str);//Get the length of the string;
//loop randomly extracts four-bit letters and numbers defined earlier;
for (i=1;i<=4;i++)
{
Num=rand (0,L-1);
//randomly extracting one digit at a time, from the first word to the maximum length of the string,
//minus 1 because the Intercept character starts from 0; Such 34 characters may be in the line;
Authnum_session.= Str[num]; The
//will be Fulianqi by the number of words to be four bits altogether;
}
Session_register ("authnum_session");
//Use session to do validation is also good; Register session, name is Authnum_session,
// Other pages can be called by _session["Authnum_session" if they contain the image
// Generate a Captcha picture,
Srand (Double) microtime () *1000000);
im = Imagecreate (50,20);//Picture width and height;
The main use of black and white gray three colors;
Black = Imagecolorallocate (IM, 0,0,0);
White = Imagecolorallocate (IM, 255,255,255);
Gray = Imagecolorallocate (IM, 200,200,200);
Drawing a four-bit integer verification code into a picture
Imagefill (Im,68,30,gray);
If you do not have to interfere with the line, the comment is OK;
Li = Imagecolorallocate (IM, 220,220,220);
for (i=0;i<3;i++)
{//Add 3 lines of interference, or do not; Depending on the circumstances, as it may affect user input;
Imageline (Im,rand (0,30), Rand (0,21), Rand (20,40), Rand (0,21), Li);
}
The position of the character in the picture;
Imagestring (IM, 5, 8, 2, authnum_session, white);
for (i=0;i<90;i++)
{//Add interfering pixels
Imagesetpixel (IM, rand ()%70, Rand ()%30, Gray);
}
Imagepng (IM);
Imagedestroy (IM);
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The above code, refer to the following article:
PHP Image Verification Code
Example of PHP generated verification code
Generate a snowflake background verification code with PHP
2. Call the Verification code page sessionvalidate.php
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Session_Start ();
At the beginning of the page to open the session,
Error_reporting (2047);
Session_destroy ();
Remove the session to get a new session value each time;
With seesion effect is good, also very convenient
?>
Session Picture Verification Example
This example validates an instance of the session
Print the previous session;
echo "Last SESSION:". _session["Authnum_session"]. "
";
Validate= "";
if (Isset (_post["Validate")) {
validate=_post["Validate"];
echo "You have just entered:". _post["Validate"]. "
Status: ";
if (validate!=_session["Authnum_session"]) {
Determine if the session value is consistent with the user input verification code;
echo "Incorrect input";
}else{
echo "Pass verification";
}
}
/*
Print all session;
Printarr (_session);
function Printarr (Aarray) {
Echo ' '; &lt;br/&gt; Print_r (aarray); &lt;br/&gt; Echo ' ;
}
*/
?> |
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