PHP應用
<div class="demo">
 <h3>1、數字驗證碼</h3>
 <p>驗證碼：<input type="text" class="input" id="code_num" name="code_num" maxlength="4" /> <img src="code_num.php" id="getcode_num" title="看不清,點擊換一張" align="absmiddle" /></p>
 <p><input type="button" class="btn" id="chk_num" value="提交" /></p>
 </div>
 <div class="demo">

PHP應用
 <h3>2、數字+字母驗證碼</h3>
 <p>驗證碼：<input type="text" class="input" id="code_char" maxlength="4" /> <img src="code_char.php" id="getcode_char" title="看不清,點擊換一張" align="absmiddle" /></p>
 <p><input type="button" class="btn" id="chk_char" value="提交" /></p>
 </div>
 <div class="demo">

PHP應用
 <h3>3、中文驗證碼</h3>
 <p>驗證碼：<input type="text" class="input" id="code_zh" maxlength="4" /> <img src="code_zh.php" id="getcode_zh" title="看不清,點擊換一張" align="absmiddle" /></p>
 <p><input type="button" class="btn" id="chk_zh" value="提交" /></p>
 </div>
 <div class="demo">

PHP應用
 <h3>4、仿google驗證碼</h3>
 <p>驗證碼：<input type="text" class="input" id="code_gg" maxlength="4" /> <img src="code_gg.php" id="getcode_gg" title="看不清,點擊換一張" align="absmiddle" /></p>
 <p><input type="button" class="btn" id="chk_gg" value="提交" /></p>
 </div>
 <div class="demo">

PHP應用
<h3>5、算術驗證碼</h3>
 <p>驗證碼：<input type="text" class="input" id="code_math" maxlength="4" /> <img src="code_math.php" id="getcode_math" title="看不清,點擊換一張" align="absmiddle" /></p>
 <p><input type="button" class="btn" id="chk_math" value="提交" /></p>
</div>

PHP應用
$(function() {
 $("#getcode_num").click(function() { //數字驗證
 $(this).attr("src", 'code_num.php?' + Math.random());
 });
 $("#chk_num").click(function() {
 var code_num = $("#code_num").val();
 $.post("chk_code.php?act=num", {
  code: code_num
 },
 function(msg) {
  if (msg == 1) {
  alert("驗證碼正確!");
  } else {
  alert("驗證碼錯誤!");
  }
 });
 });

PHP應用
 $("#getcode_char").click(function() {
 $(this).attr("src", 'code_char.php?' + Math.random());
 });
 $("#chk_char").click(function() {
 var code_char = $("#code_char").val();
 $.post("chk_code.php?act=char", {
  code: code_char
 },
 function(msg) {
  if (msg == 1) {
  alert("驗證碼正確!");
  } else {
  alert("驗證碼錯誤!");
  }
 });
 });

PHP應用
 $("#getcode_zh").click(function() {
 $(this).attr("src", 'code_zh.php?' + Math.random());
 });
 $("#chk_zh").click(function() {
 var code_zh = escape($("#code_zh").val());
 $.post("chk_code.php?act=zh", {
  code: code_zh
 },
 function(msg) {
  if (msg == 1) {
  alert("驗證碼正確!");
  } else {
  alert("驗證碼錯誤!");
  }
 });
 });

PHP應用
 $("#getcode_gg").click(function() {
 $(this).attr("src", 'code_gg.php?' + Math.random());
 });
 $("#chk_gg").click(function() {
 var code_gg = $("#code_gg").val();
 $.post("chk_code.php?act=gg", {
  code: code_gg
 },
 function(msg) {
  if (msg == 1) {
  alert("驗證碼正確!");
  } else {
  alert("驗證碼錯誤!");
  }
 });
 });

PHP應用
 $("#getcode_math").click(function() {
 $(this).attr("src", 'code_math.php?' + Math.random());
 });
 $("#chk_math").click(function() {
 var code_math = $("#code_math").val();
 $.post("chk_code.php?act=math", {
  code: code_math
 },
 function(msg) {
  if (msg == 1) {
  alert("驗證碼正確!");
  } else {
  alert("驗證碼錯誤!");
  }
 });
 });
});

PHP應用
session_start();
getCode(4,60,20);
function getCode($num,$w,$h) {
 $code = "";
 for ($i = 0; $i < $num; $i++) {
 $code .= rand(0, 9);
 }
 //4位驗證碼也可以用rand(1000,9999)直接生成
 //將生成的驗證碼寫入session,備驗證時用
 $_SESSION["helloweba_num"] = $code;
 //創建圖片,定義顏色值
 header("Content-type: image/PNG");
 $im = imagecreate($w, $h);
 $black = imagecolorallocate($im, 0, 0, 0);
 $gray = imagecolorallocate($im, 200, 200, 200);
 $bgcolor = imagecolorallocate($im, 255, 255, 255);
 //填充配景
 imagefill($im, 0, 0, $gray);
 //畫邊框
 imagerectangle($im, 0, 0, $w-1, $h-1, $black);
 //隨機繪制兩條虛線,起干擾作用
 $style = array ($black,$black,$black,$black,$black,
 $gray,$gray,$gray,$gray,$gray
 );
 imagesetstyle($im, $style);
 $y1 = rand(0, $h);
 $y2 = rand(0, $h);
 $y3 = rand(0, $h);
 $y4 = rand(0, $h);
 imageline($im, 0, $y1, $w, $y3, IMG_COLOR_STYLED);
 imageline($im, 0, $y2, $w, $y4, IMG_COLOR_STYLED);
 //在畫布上隨機生成大量黑點,起干擾作用;
 for ($i = 0; $i < 80; $i++) {
 imagesetpixel($im, rand(0, $w), rand(0, $h), $black);
 }
 //將數字隨機顯示在畫布上,字符的水平間距和位置都按一定波動范圍隨機生成
 $strx = rand(3, 8);
 for ($i = 0; $i < $num; $i++) {
 $strpos = rand(1, 6);
 imagestring($im, 5, $strx, $strpos, substr($code, $i, 1), $black);
 $strx += rand(8, 12);
 }
 imagepng($im);//輸出圖片
 imagedestroy($im);//釋放圖片所占內存
}