core-bundle/src/Resources/contao/forms/FormCaptcha.php
public function generate()
	{
		return sprintf('<input type="text" name="%s" id="ctrl_%s" class="captcha mandatory%s" value="" aria-describedby="captcha_text_%s"%s%s',
						$this->strCaptchaKey,
						$this->strId,
						(($this->strClass != '') ? ' ' . $this->strClass : ''),
						$this->strId,
						$this->getAttributes(),
						$this->strTagEnding);
	}
public function generate()
	{
		return sprintf('<input type="text" name="%s" id="ctrl_%s" class="captcha mandatory%s" value="" aria-describedby="captcha_text_%s"%s%s',
						$this->strCaptchaKey,
						$this->strId,
						(($this->strClass != '') ? ' ' . $this->strClass : ''),
						$this->strId,
						$this->getAttributes(),
						$this->strTagEnding);
	}
Generate the widget and return it as string

@return string The widget markup