PHP Verification Code generation and verification example

Last Update:2017-01-13 Source: Internet

Author: User

Tags rand strlen

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11 Simple example of a verification code

1.1 Picture of the verification code displayed

The code is as follows	Copy Code
<?php $num =intval (Mt_rand (1000,9999)); for ($i =0; $i <4; $i + +) {echo " ";} ?>

1.2 Verification process

The code is as follows	Copy Code
if (Strval ($INPUTYZM)!=strval ($num)) { echo "<script>alert (' CAPTCHA error!) '); History.go ( -1);</script> "; Exit }

A verification code example for 21 Chinese characters

2.1 Picture of the verification code displayed

The code is as follows	Copy Code
<?php $str = "Han", "word", "examination", "proof", "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]; } >

2.2 Assign the generated random string to a hidden field

The code is as follows	Copy Code
<input type= "hidden" name= "Yzm" value= "<?php echo $pic;?/>" >

2.3 Define a check () function

code is as follows	copy code
<script language= "javascript" function Check (form) { if (form.yzm.value== "") { alert ("Please enter a validation code"); Form.yzm.focus (); return false; } if (form.yzm.vale!=form.yz.value) {alert ("Authenticode error"); Form.yzm.focus (); return false; } } </script>

Look at a complete example

PHP Verification code generation and invocation of examples, usually in the development of the use, recorded.

1. Verification code Generation file code.php

The code is as follows

Copy Code

?
Header ("Content-type:image/png");
Define header, declare picture file, preferably PNG, no copyright disturbance;
To generate a new four-bit integer verification code
Session_Start ()//open session;
Authnum_session = ';
str = ' abcdefghijkmnpqrstuvwxyz1234567890 ';
Define the numbers and letters to be displayed on the picture;
L = strlen (str); Gets the length of the string;
The loop randomly extracts the four-bit previously defined letters and numbers;
for (i=1;i<=4;i++)
{
Num=rand (0,L-1);
Randomly extract one digit at a time, from the first word to the maximum length of the string,
Minus 1 is because the Intercept character starts at 0, so that 34 characters may be in the line.
Authnum_session.= Str[num];
will be through the number of words Fulianqi to a total of four bits;
}
Session_register ("Authnum_session");
Use the session to do verification is also good; Register session, name is Authnum_session,
Other pages just include the picture
That is, you can call it by _session["Authnum_session"]

Generate a Captcha picture,
Srand (Double) microtime () *1000000);
im = Imagecreate (50,20);//Picture wide and high;
Mainly used in black and white gray three kinds of color;
Black = Imagecolorallocate (IM, 0,0,0);
White = Imagecolorallocate (IM, 255,255,255);
Gray = Imagecolorallocate (IM, 200,200,200);
To draw a four-bit integer verification code into a picture
Imagefill (Im,68,30,gray);
If you do not need to disturb the line, comments on the line;
Li = Imagecolorallocate (IM, 220,220,220);
for (i=0;i<3;i++)
{//Add 3 interference lines; it may not, depending on the circumstances, because it may affect user input;
Imageline (Im,rand (0,30), Rand (0,21), Rand (20,40), Rand (0,21), Li);
}
character in the position of the picture;
Imagestring (IM, 5, 8, 2, authnum_session, white);
for (i=0;i<90;i++)
{//Add interference pixels
Imagesetpixel (IM, rand ()%70, Rand ()%30, Gray);
}
Imagepng (IM);
Imagedestroy (IM);
?>

The above code, refer to the following article:
PHP Picture Verification Code
Example of PHP generating verification code
Generate a validation code with a snowflake background in PHP

2, call the Verification code page sessionvalidate.php

The code is as follows

Copy Code

<?php
Session_Start ();
In the page first to open session,
Error_reporting (2047);
Session_destroy ();
The session is removed so that a new session value can be taken each time;
With seesion effect is good, also very convenient
?>
<title>session Picture Validation Example </title>
<body>
This example is the session validation instance
<form action= "" method= "POST" >
Verify code: <input type= "text" name= "Validate" value= "" Size=10> <br>
<input type= "Submit" >
</form>
<?php
Print the previous session;
echo "Prev session:<b>". _session["Authnum_session". " </b><br> ";
Validate= "";
if (Isset (_post["validate"])) {
validate=_post["Validate"];
echo "You just entered is:". _post["Validate"]. " <br> Status: ";
if (validate!=_session["Authnum_session"]) {
To determine whether the session value is consistent with the user's input validation code;
echo "<font color=red> input error </font>";
}else{
echo "<font color=green> through validation </font>";
}
}
/*
Print all sessions;
Printarr (_session);
function Printarr (Aarray) {
Echo ' <xmp> ';
Print_r (Aarray);
Echo ' </xmp> ';
}
*/
?>

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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