08-04-15.html

> with(StringTools):

> Caesar := proc(plain, shift)
  local numlist;
  numlist:=convert(plain, bytes);
   convert( [ seq(modp(numlist[i]+shift, 127), i=1..nops(numlist))], bytes);
end:

> Caesar("Yo' mommy so fat that...",-32);

(1)

> Caesar("Yo' mommy so fat that...",-12);

$McacaamgcZUhh\Uh$ (2)

> convert("Yo' mommy", bytes);

(3)

> Caesar("Yo' mommy so fat that...",95);

(4)

> Caesar := proc(plain, shift)
  local numlist;
  numlist:=convert(plain, bytes);
   convert( [ seq(modp(numlist[i]+shift-1, 127)+1, i=1..nops(numlist))], bytes);
end:

> Caesar("Yo' mommy so fat that...",95);

(5)

> IsPrintable("a");

(6)

> convert([5],bytes);

(7)

> IsPrintable(convert([5],bytes));

(8)

> Alphabet:="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*()_+-=;:' ?<>,\".";

(9)

> length(Alphabet);

(10)

> SearchText("p", Alphabet);

(11)

> SearchText("a", Alphabet);

(12)

> SearchText(".", Alphabet);

(13)

> SearchText("Howdy", Alphabet);

(14)

> word:="Howdy";

(15)

> word[1];

(16)

> word[5];

(17)

> seq(word[i],i=1..length(word));

(18)

> StringToList := proc(text)
global Alphabet;
return(
[seq( SearchText(text[i], Alphabet) ,i=1..length(text))] );
end;

(19)

> StringToList("Howdy");

(20)

> StringToList(3);

Error, (in StringToList) invalid arguments for searchtext

> StringToList := proc(text::string)
global Alphabet;
return(
[seq( SearchText(text[i], Alphabet) ,i=1..length(text))] );
end;

(21)

> StringToList(3);

Error, invalid input: StringToList expects its 1st argument, text, to be of type string, but received 3

> StringToList("3");

(22)

> ListToString := proc( numlist )
global Alphabet;
seq( Alphabet[numlist[i]], i=1..nops(numlist) );
end:

> ListToString([3,5,1]);

(23)

> cat(%);

(24)

> ListToString := proc( numlist )
global Alphabet;
cat( seq( Alphabet[numlist[i]], i=1..nops(numlist) ) );
end:

> ListToString ( [0, -7, 512, 6 ]);

Error, (in ListToString) invalid range for string subscript

> ListToString ( "Henry");

Error, (in ListToString) invalid string subscript selector

> ListToString := proc( numlist :: list(posint))
global Alphabet;
cat( seq( Alphabet[numlist[i]], i=1..nops(numlist) ) );
end:

> ListToString ( "Henry");

Error, invalid input: ListToString expects its 1st argument, numlist, to be of type list(posint), but received Henry

> ListToString ( [0, -7, 512, 6 ]);

Error, invalid input: ListToString expects its 1st argument, numlist, to be of type list(posint), but received [0, -7, 512, 6]

> ListToString ( [1, 7, 512, 6 ]);

(25)

> Alphabet;

(26)

> Julius := proc( plain::string, shift::integer)
local nums,crypt, i;
global Alphabet;
nums := StringToList(plain);
crypt := ListToString( [ seq(nums[i] + shift, i=1..nops(nums)) ] );
return(crypt);
end:

> Julius("hide me. Please, I'm SCARED!", 1);

(27)

> Julius(%, -1);

(28)

> Julius("hide me. Please, I'm SCARED!", 75);

(29)

> Julius(%, -75);

(30)

> Julius := proc( plain::string, shift::integer)
local nums,crypt, i;
global Alphabet;
nums := StringToList(plain);
crypt := ListToString(   [ seq(
                              modp(nums[i] + shift -1, length(Alphabet)) +1,
                              i=1..nops(nums)) ] );
return(crypt);
end:

> Julius("hide me. Please, I'm SCARED!", 75);

(31)