PHP simple verification code generation example_PHP tutorial

Verification codes can prevent some users from repeatedly submitting to guess passwords or using brute force tools to guess passwords. After we added verification codes, it made it more difficult for them. Below I provide a session-based verification code program.

When logging in and registering on a website, verification codes are often used to prevent others from using mechanical violence to register or log in. Adding the verification code makes the website much safer to a certain extent. The following is a relatively simple verification code generation, which also provides session assignment.

The code is as follows

代码如下

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session_start(); header(“Content-type: image/png”); //创建真彩色白纸 $im = @imagecreatetruecolor(50, 20) or die(“建立图像失败”); //获取背景颜色 $background_color = imagecolorallocate($im, 255, 255, 255); //填充背景颜色(这个东西类似油桶) imagefill($im,0,0,$background_color); //获取边框颜色 $border_color = imagecolorallocate($im,200,200,200); //画矩形，边框颜色200,200,200 imagerectangle($im,0,0,49,19,$border_color); //逐行炫耀背景，全屏用1或0 for($i=2;$i<18;$i++){ //获取随机淡色 $line_color = imagecolorallocate($im,rand(200,255),rand(200,255),rand(200,255)); //画线 imageline($im,2,$i,47,$i,$line_color); } //设置字体大小 $font_size=12; //设置印上去的文字 $Str[0] = “ABCDEFGHIJKLMNOPQRSTUVWXYZ”; $Str[1] = “abcdefghijklmnopqrstuvwxyz”; $Str[2] = “01234567891234567890123456″; //获取第1个随机文字 $imstr[0]["s"] = $Str[rand(0,2)][rand(0,25)]; $imstr[0]["x"] = rand(2,5); $imstr[0]["y"] = rand(1,4); //获取第2个随机文字 $imstr[1]["s"] = $Str[rand(0,2)][rand(0,25)]; $imstr[1]["x"] = $imstr[0]["x"]+$font_size-1+rand(0,1); $imstr[1]["y"] = rand(1,3); //获取第3个随机文字 $imstr[2]["s"] = $Str[rand(0,2)][rand(0,25)]; $imstr[2]["x"] = $imstr[1]["x"]+$font_size-1+rand(0,1); $imstr[2]["y"] = rand(1,4); //获取第4个随机文字 $imstr[3]["s"] = $Str[rand(0,2)][rand(0,25)]; $imstr[3]["x"] = $imstr[2]["x"]+$font_size-1+rand(0,1); $imstr[3]["y"] = rand(1,3); //将显示的数组赋值给session $_SESSION['CODE'] = $imstr[0]["s"].$imstr[1]["s"].$imstr[2]["s"].$imstr[3]["s"]; //写入随机字串 for($i=0;$i<4;$i++){ $text_color = imagecolorallocate($im,rand(50,180),rand(50,180),rand(50,180)); imagechar($im,$font_size,$imstr[$i]["x"],$imstr[$i]["y"],$imstr[$i]["s"],$text_color); } //显示图片 imagepng($im); //销毁图片 imagedestroy($im); ?>

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session_start();

header(“Content-type: image/png”);

//Create true color white paper $im = @imagecreatetruecolor(50, 20) or die("Failed to create image"); //Get the background color $background_color = imagecolorallocate($im, 255, 255, 255); //Fill the background color (this thing is similar to an oil drum) imagefill($im,0,0,$background_color); //Get the border color $border_color = imagecolorallocate($im,200,200,200); //Draw a rectangle, border color 200,200,200 imagerectangle($im,0,0,49,19,$border_color); //Show off the background line by line, use 1 or 0 for full screen for($i=2;$i<18;$i++){

//Get random light color

$line_color = imagecolorallocate($im,rand(200,255),rand(200,255),rand(200,255));