initialising variables
$ a = 1 ; $ b = 2 ; $ c = 3 ; $ d = 4 ; echo " Values ▁ before ▁ swapping ▁ are ▁ : " , " STRNEWLINE " ; echo " a = " ▁ , ▁ $ a ▁ , " " ; STRNEWLINE echo ▁ " b = " ▁ , $ b , " " ; STRNEWLINE echo ▁ " c = " ▁ , ▁ $ c ▁ , " " ; STRNEWLINE echo ▁ " d = " ▁ , ▁ $ d ▁ , " " , " "