RosettaCodeData/Task/Caesar-cipher/XPL0/caesar-cipher.xpl0

code ChIn=7, ChOut=8, IntIn=10;
int  Key, C;
[Key:= IntIn(8);
repeat  C:= ChIn(1);
        if C>=^a & C<=^z then C:= C-$20;
        if C>=^A & C<=^Z then
            [C:= C+Key;
            if C>^Z then C:= C-26
            else if C<^A then C:= C+26;
            ];
        ChOut(0, C);
until   C=$1A; \EOF
]