entry trim;
begin "trim"
   define library!entry = true;
   require "sys:std.hdr" source!file;
   internal simple string procedure trim(string x);
   begin "trim"
      ! TRIM returns a copy of its argument with leading and trailing
        blanks removed. If the string is all blank then the
        null string will be returned. If the original
        string was null then the result will also be null;

      while (length(x) > 1) and (x[1 for 1] = " ") do
           x ← x[2 to inf];
      while (length(x) > 1) and (x[inf for 1] = " ") do
           x ← x[1 to inf-1];
      if equ(x," ") then
           x := null;
      return(x);
   end "trim";
end "trim"