s := "x" ----> "x" s ++:= "x" ----> 'x' s ----> 'x' s := "x" ----> "x" s ++:= "xx" ----> 'x' s ----> 'x' s := "x" ----> "x" s ++:= "X" ----> 'Xx' s ----> 'Xx' s := "x" ----> "x" s ++:= "abc" ----> 'abcx' s ----> 'abcx' s := "x" ----> "x" s --:= "x" ----> '' s ----> '' s := "x" ----> "x" s --:= "xx" ----> '' s ----> '' s := "x" ----> "x" s --:= "X" ----> 'x' s ----> 'x' s := "x" ----> "x" s --:= "abc" ----> 'x' s ----> 'x' s := "x" ----> "x" s **:= "x" ----> 'x' s ----> 'x' s := "x" ----> "x" s **:= "xx" ----> 'x' s ----> 'x' s := "x" ----> "x" s **:= "X" ----> '' s ----> '' s := "x" ----> "x" s **:= "abc" ----> '' s ----> '' Run-time error 102 at line 45 in expr52.icn numeric expected offending value: ""