What to do if php cannot generate images

Solution to the problem that php cannot generate images: 1. Open the gd2 library; 2. Delete all output before generating images; 3. Clear the output cache through "ob_clean();".

The operating environment of this article: Windows 7 system, PHP version 7.1, DELL G3 computer

What should I do if php cannot generate images? The PHP verification code cannot generate images, the reason is solved

When generating images, header('Content-type: image/png'); cannot have output in front! ! !

Or, add: ob_clean(); Even if you use output, you can clear the output cache through this sentence! Very important! ! !

Of course, you must first open the gd2 library, which can be viewed through phpinfo. After clearing the BOM, the code is also written starting from the top line, so the problem may occur in the code. After some research, I found that I still need to change the program and add the ob_clean() statement in front of the header, so that it can run! Haha, coding and debugging programs is like being a doctor, and you will become strong with practice.

        

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Set string color

$str_color = imageColorAllocate($img, mt_rand(0, 100), mt_rand(0, 100),mt_rand(0, 100)); //设定字符串位置 $font_w = imageFontWidth($font); //字体宽 $font_h = imageFontHeight($font); //字体高 $str_w = $font_w * $char_len; //字符串宽 imageString($img, $font, ($img_w-$str_w)/2, ($img_h-$font_h)/2, $code, $str_color); echo 'ddd'; //输出影响生成图片，查找了大半天的原因终于找到了 ob_clean(); //也可以加上这句，这样前面有输出，清除输出缓存 //生成图片 header ( 'Content-Type: image/png' );//header前不能加任何输出或加ob_clean()清除 imagepng($img); //----4 销毁画布 imagedestroy($img);

Recommended learning: "PHP Video Tutorial"

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