How to generate CAPTCHA automatically by php

This article mainly explains "how to automatically generate CAPTCHA by php". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "how to generate CAPTCHA automatically by php".

Php implements the method of automatically generating CAPTCHA: [session_start (); $width = 150; $height = 40; $image = imagecreatetruecolor ($width, $height); $bgcol...].

This article operating environment: windows10 system, php 7, thinkpad T480 computer.

Now there are more and more applications of CAPTCHA in the form, but it is always inconvenient to use js to achieve it, so use php to achieve it, and record it here.

Of course, we can also encapsulate it into a function, which is also very convenient to use in the future. It is not encapsulated here, and interested partners can encapsulate it themselves.

Specific implementation code:

Create a new cap_sz.php file:

/ / No less here, otherwise garbled verification code test

CAPTCHA:

Click on the picture to change the CAPTCHA

Please enter the contents of the picture:

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