Verification code is a common function in WEB2.0 now. Registration, login or message pages all require a registration code to verify the legitimacy of the current operator. We will see that some websites do not have verification codes. , but that is a more advanced verification. Let’s look at the commonly used verification code generation and usage methods.
1 A simple verification code example
1.1 Picture showing verification code
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for($i=0; $i<4;$i++) {echo "";} ?>
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if (strval($inputyzm)!=strval($num)) |
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if (strval($inputyzm)!=strval($num)) |
2 A Chinese character verification code example
2.1 Picture showing verification code
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$str="汉","字","验","证","码"); //可以定义汉字的内容和个数 $word=strlen($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
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代码如下 | 复制代码 |
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See a complete example
Examples of generating and calling PHP verification codes, which are often used in daily development. Please record them.
1. Verification code generation file code.php
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Header("Content-type:image/png"); //Define header, declare image file, preferably png, no copyright interference; //Generate a new four-digit integer verification code Session_start();//Open session; authnum_session = ''; str = 'abcdefghijkmnpqrstuvwxyz1234567890'; //Define the numbers and letters used to display on the picture; l = strlen(str); //Get the length of the string; //Loop and randomly select four letters and numbers defined previously; for(i=1;i<=4;i++) { num=rand(0,l-1); // Randomly select a number each time; from the first word to the maximum length of the string, //Minus 1 because the intercepted characters start from 0; in this way, any 34 characters may be ranked among them; authnum_session.= str[num]; //The characters obtained by numbers are connected to a total of four digits; } Session_register("authnum_session"); //It’s also good to use session for verification; register session, the name is authnum_session, //As long as other pages contain this image //You can call <🎜> through _SESSION["authnum_session"] <🎜> //Generate verification code image, srand((double)microtime()*1000000); im = imagecreate(50,20);//Picture width and height; //Mainly use three colors: black, white and gray; Black = ImageColorAllocate(im, 0,0,0); White = ImageColorAllocate(im, 255,255,255); Gray = ImageColorAllocate(im, 200,200,200); //Draw the four-digit integer verification code into the picture Imagefill(im,68,30,gray); //If no interference lines are needed, just comments; li = ImageColorAllocate(im, 220,220,220); for(i=0;i<3;i++) {//Add 3 interference lines; it may not be necessary; it depends on the situation, because 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 interference pixels imagesetpixel(im, rand()%70, rand()%30, gray); } ImagePNG(im); ImageDestroy(im); ?> |
The above code refers to the following article:
php image verification code
Example of php generating verification code
Use php to generate verification code with snowflake background
2. The page that calls the verification code sessionValidate.php
The code is as follows
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//On the page, you must first open the session,
echo "Previous session:"._SESSION["authnum_session"]."