What should I do if the php verification code image cannot be displayed?

The solution to the problem that the php verification code image cannot be displayed: first open the corresponding PHP file; then add the code as "ob_clean();" before the header output; finally save the modification.

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

PHP verification code image cannot be displayed

I thought the gd2 library was not opened, but I checked with phpinfo and found that it was opened.

Solution

Add before the header output :

ob_clean(); //关键代码，防止出现'图像因其本身有错无法显示'的问题。
header("Content-type:image/jpeg");

Example:

  private function outPut() {
        ob_clean();  //关键代码，防止出现'图像因其本身有错无法显示'的问题。
        header('Content-type:image/png');
        imagepng($this->img);
        imagedestroy($this->img);
    }

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