On windows.
When you get undefined function image* it means the gd library isnt being used. Check the php.ini file. Make sure the php_gd.dll isnt commented out. Restarting apache should result in the image functions working.
xampp\php\php.ini
;extension=gd -> extension=gd
delete ";"
<?php
header("Content-Type: image/png");
$im = @imagecreate(110, 20)
or die("Cannot Initialize new GD image stream");
$background_color = imagecolorallocate($im, 0, 0, 0);
$text_color = imagecolorallocate($im, 233, 14, 91);
imagestring($im, 1, 5, 5, "A Simple Text String", $text_color);
imagepng($im);
imagedestroy($im);
?>
操作介面：「captcha_index.php」
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>php圖形驗證碼</title>
<script>
function refresh_code(){
document.getElementById("imgcode").src="captcha.php";
}
</script>
</head>
<body>
<form name="form1" method="post" action="./checkcode.php">
<p>請輸入下圖字樣：</p><p><img id="imgcode" src="captcha.php" onclick="refresh_code()" /><br />
點擊圖片可以更換驗證碼
</p>
<input type="text" name="checkword" size="10" maxlength="10" />
<input type="submit" name="Submit" value="送出" />
</form>
</body>
</html>產生驗證碼：「captcha.php」
<?php
if(!isset($_SESSION)){ session_start(); } //檢查SESSION是否啟動
$_SESSION['check_word'] = ''; //設置存放檢查碼的SESSION
//設置定義為圖片
header("Content-type: image/PNG");
/*
imgcode($nums,$width,$high)
設置產生驗證碼圖示的參數
$nums 生成驗證碼個數
$width 圖片寬
$high 圖片高
*/
imgcode(5,120,30);
//imgcode的function
function imgcode($nums,$width,$high) {
//去除了數字0和1 字母小寫O和L，為了避免辨識不清楚
$str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMOPQRSTUBWXYZ";
$code = '';
for ($i = 0; $i < $nums; $i++) {
$code .= $str[mt_rand(0, strlen($str)-1)];
}
$_SESSION['check_word'] = $code;
//建立圖示，設置寬度及高度與顏色等等條件
$image = imagecreate($width, $high);
$black = imagecolorallocate($image, mt_rand(0, 200), mt_rand(0, 200), mt_rand(0, 200));
$border_color = imagecolorallocate($image, 21, 106, 235);
$background_color = imagecolorallocate($image, 235, 236, 237);
//建立圖示背景
imagefilledrectangle($image, 0, 0, $width, $high, $background_color);
//建立圖示邊框
imagerectangle($image, 0, 0, $width-1, $high-1, $border_color);
//在圖示布上隨機產生大量躁點
for ($i = 0; $i < 80; $i++) {
imagesetpixel($image, rand(0, $width), rand(0, $high), $black);
}
$strx = rand(3, 8);
for ($i = 0; $i < $nums; $i++) {
$strpos = rand(1, 6);
imagestring($image, 5, $strx, $strpos, substr($code, $i, 1), $black);
$strx += rand(10, 30);
}
imagepng($image);
imagedestroy($image);
}
?>驗證輸入的驗證碼是否正確：「checkcode.php」
<?php
if(!isset($_SESSION)){
session_start();
} //判斷session是否已啟動
if((!empty($_SESSION['check_word'])) && (!empty($_POST['checkword']))){ //判斷此兩個變數是否為空
if($_SESSION['check_word'] == $_POST['checkword']){
$_SESSION['check_word'] = ''; //比對正確後，清空將check_word值
header('content-Type: text/html; charset=utf-8');
echo '<p> </p><p> </p><a href="./chptcha_index.php">OK輸入正確，將於一秒後跳轉(按此也可返回)</a>';
echo '<meta http-equiv="refresh" content="1; url=./captcha_index.php">';
exit();
}else{
echo '<p> </p><p> </p><a href="./chptcha_index.php">Error輸入錯誤，將於一秒後跳轉(按此也可返回)</a>';
echo '<meta http-equiv="refresh" content="1; url=./captcha_index.php">';
}
}
?>
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