How to Install and Configure think-captcha in ThinkPHP

Step 1: Install the think-captcha package via Composer using composer require topthink/think-captcha .

Step 2: Configure the captcha parameters by editing config/captcha.php , for example setting 'length' => 4 and 'codeSet' => '0123456789' to generate a 4‑digit numeric code.

Step 3: Generate the captcha in a controller, e.g.:

<?php
namespace app\index\controller;
use think\captcha\facade\Captcha;
class Index{
    public function verify(){
        return Captcha::create();
    }
}

Step 4: Display the captcha in a view by adding {:captcha_img()} or <img src="{:captcha_src()}" alt="captcha" /> to the template.

Step 5: Access the URL http://YourUrl/index/index/verify to see the generated captcha.

Step 6: Define a route for the captcha, for example Route::get('captcha/[:config]', '\\think\\captcha\\CaptchaController@index'); .

Step 7: Verify the user input with either $captcha = new Captcha(); if(!$captcha->check($value)){ /* verification failed */ } or the helper if(!captcha_check($value)){ /* verification failed */ } .