php验证码权限被拒绝

您从未定义

$img\u文件

。您应该在此处定义路径，例如：

<?php
session_start();
if(isset($_POST["captcha"])) {
    if(($_SESSION['captcha_code'] == $_POST['captcha']) && (!empty($_SESSION['captcha_code'])) ) {
        //Passed!
        $captcha_msg="Thank you";
    }else{
        // Not passKed 8-(
        $captcha_msg="invalid code";
        if(isset($_POST["MM_insert"])){
            unset($_POST["MM_insert"]);
        }
        if(isset($_POST["MM_update"])){
            unset($_POST["MM_update"]);
        }
    }
}
class CaptchaImage {
    var $font = "verdana.ttf";
    function hex_to_dec($hexcolor){
    //convert hex hex values to decimal ones
    $dec_color=array('r'=>hexdec(substr($hexcolor,0,2)),'g'=>hexdec(substr($hexcolor,2,2)),'b'=>hexdec(substr($hexcolor,4,2)));
    return $dec_color;
    }
    function generateCode($characters) {
        /* list all possible characters, similar looking characters and vowels have been removed */
        $possible = '23456789bcdfghjkmnpqrstvwxyz'; 
        $code = '';
        $i = 0;
        while ($i < $characters) { 
            $code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
            $i++;
        }
        return $code;
    }
    function CaptchaImage($width='120',$height='30',$characters='6',$hex_bg_color='FFFFFF',$hex_text_color="FF0000",$hex_noise_color="CC0000", $img_file='captcha.jpg') {
        $rgb_bg_color=$this->hex_to_dec($hex_bg_color);
        $rgb_text_color=$this->hex_to_dec($hex_text_color);
        $rgb_noise_color=$this->hex_to_dec($hex_noise_color);
        $code = $this->generateCode($characters);
        /* font size will be 60% of the image height */
        $font_size = $height * 0.60;
        $image = @imagecreate($width, $height) or die('Cannot Initialize new GD image stream');
        /* set the colours */
        $background_color = imagecolorallocate($image, $rgb_bg_color['r'], $rgb_bg_color['g'],$rgb_bg_color['b']);
        $text_color = imagecolorallocate($image, $rgb_text_color['r'], $rgb_text_color['g'],$rgb_text_color['b']);
        $noise_color = imagecolorallocate($image, $rgb_noise_color['r'], $rgb_noise_color['g'],$rgb_noise_color['b']);
        /* generate random dots in background */
        for( $i=0; $i<($width*$height)/3; $i++ ) {
            imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);
        }
        /* generate random lines in background */
        for( $i=0; $i<($width*$height)/150; $i++ ) {
            imageline($image, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $noise_color);
        }
        /* create textbox and add text */
        $textbox = imagettfbbox($font_size, 0, $this->font, $code);
        $x = ($width - $textbox[4])/2;
        $y = ($height - $textbox[5])/2;
        imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code);
        /* save the image */
        imagejpeg($image,$img_file);
        imagedestroy($image);
        echo "<img src=\"$img_file?".time()."\" width=\"$width\" height=\"$height\" alt=\"security code\" id=\"captchaImg\">";
        $_SESSION['captcha_code'] = $code;
    }

}

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还要确保路径是可写的。

告诉我们调用此函数的位置

$img_file = 'picture.jpg';
imagejpeg($image,$img_file);
....