core-bundle/src/Resources/contao/library/Contao/Input.php
public static function post($strKey, $blnDecodeEntities=false)
	{
		$strCacheKey = $blnDecodeEntities ? 'postDecoded' : 'postEncoded';

		if (!isset(static::$arrCache[$strCacheKey][$strKey]))
		{
			$varValue = static::findPost($strKey);

			if ($varValue === null)
			{
				return $varValue;
			}

			$varValue = static::decodeEntities($varValue);
			$varValue = static::xssClean($varValue, true);
			$varValue = static::stripTags($varValue);

			if (!$blnDecodeEntities)
			{
				$varValue = static::encodeSpecialChars($varValue);
			}

			if (!\defined('TL_MODE') || TL_MODE != 'BE')
			{
				$varValue = static::encodeInsertTags($varValue);
			}

			static::$arrCache[$strCacheKey][$strKey] = $varValue;
		}

		return static::$arrCache[$strCacheKey][$strKey];
	}
public static function post($strKey, $blnDecodeEntities=false)
	{
		$strCacheKey = $blnDecodeEntities ? 'postDecoded' : 'postEncoded';

		if (!isset(static::$arrCache[$strCacheKey][$strKey]))
		{
			$varValue = static::findPost($strKey);

			if ($varValue === null)
			{
				return $varValue;
			}

			$varValue = static::decodeEntities($varValue);
			$varValue = static::xssClean($varValue, true);
			$varValue = static::stripTags($varValue);

			if (!$blnDecodeEntities)
			{
				$varValue = static::encodeSpecialChars($varValue);
			}

			if (!\defined('TL_MODE') || TL_MODE != 'BE')
			{
				$varValue = static::encodeInsertTags($varValue);
			}

			static::$arrCache[$strCacheKey][$strKey] = $varValue;
		}

		return static::$arrCache[$strCacheKey][$strKey];
	}
Return a $_POST variable

@param string  $strKey            The variable name
@param boolean $blnDecodeEntities If true, all entities will be decoded

@return mixed The cleaned variable value