/* Reverse string in place */
proc nonrec reverse(*char s) void:
    *char e;
    char t;
    e := s;
    while e* /= '\e' do
        e := e + 1
    od;
    while
        e := e - 1;
        s < e
    do
        t := e*;
        e* := s*;
        s* := t;
        s := s + 1
    od
corp

proc nonrec main() void:
    *char testString = "!dlrow ,olleH";
    reverse(testString);
    writeln(testString)
corp