Reading string one character at a time.

Okay, so the problem is, I'm reading content from a file, into a string. I need a solution that will read each character from the string, and pass it through a rot13 type of function.

So basically, I just can't figure out how to read one character from said string, at a time.


Any help is appreciated.

Thanks. :)

So what have you done so fare?

--
Mats

Honestly, I know why you're asking that, and that is to make sure I'm not getting anyone to do all the work for me.

Seeing as how I have no idea how to approach this problem, I don't have any code snippet involving it. Although I could post my whole program's source code, I choose not to, as it's a personal tool, and I don't see how it would relate to the current issue at hand.

That is indeed why I'm asking.

So, my suggestion is that you look at what options there are for reading a char at a time.

--
Mats

Code:

---

#include <iostream>
#include <string>

int main()
{
  std::string s;
  do
  {
      std::cout << "Please, if you will, enter a string of two characters or more." << std::endl;
      std::getline(std::cin, s);
  }while(s.size() < 2);
  std::cout << "Here's a hint\n"
            << "\tfirst char: " << s[0]
            << "\n\tsecond char: " << s[1] << std::endl;
}

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Well, thanks for your replies anyways, but I ended up going about solving my problem a different, and maybe more complicated than necessary way, but it works. :P

One more thing though, I have this rot13 function, which rotates a character 13 positions:

Code:

---

char rot13( char x ) {
    return ( x - 'A' + 13 ) % 26 + 'A';
}

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Say I want to decrypt a character that is encrypted using this function; how do I go about modifying the above code snippet to accomplish this?

I've already tried the obvious solution of using the opposite of the operators used, such as replacing the addition sign with a subtraction sign, etc. Although I didn't know what to replace the percent (%) sign with, I still didn't get the correct outcome.

So if anyone could provide me with a solution, it would be greatly appreciated.

Thanks in advance. :)

The whole point of rot13 is you don't change one single thing to decrypt.

Quote:

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Originally Posted by tabstop

The whole point of rot13 is you don't change one single thing to decrypt.

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Well, at first I was going to say I already tried that, and still didn't get the desired outcome.

Although it seems the problem was, that I replaced 'A' + 13 with 'A' + 18. After switching it back, it seems to be working fine.

Thanks.

The func rot13 just only encrypt 'A'~'Z',
if your just want gain that, you can deal with it like this:

Code:

---

char decrypt(char x)
{
        return (x-13)<'A'?(x-13)+26:(x-13);
}

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Just to be on the safe side, this shouldn't cause me any problems, correct?:

Code:

---

char rot13 ( char x ) {
        if (( x == 'a' ) || ( x == 'b' ) || ( x == 'c' ) || ( x == 'd' ) || ( x == 'e' ) || ( x == 'f' ) || ( x == 'g' ) || ( x == 'h' ) || ( x == 'i' ) || ( x == 'j' ) ||
        ( x == 'k' ) || ( x == 'l' ) || ( x == 'm' ) || ( x == 'n' ) || ( x == 'o' ) || ( x == 'p' ) || ( x == 'q' ) || ( x == 'r' ) || ( x == 's' ) || ( x == 't' ) ||
          ( x == 'u' ) || ( x == 'v' ) || ( x == 'w' ) || ( x == 'x' ) || ( x == 'y' ) || ( x == 'z' )) {
                  return ( x - 'a' + 13 ) % 26 + 'a';
        } else if (( x == 'A' ) || ( x == 'B' ) || ( x == 'C' ) || ( x == 'D' ) || ( x == 'E' ) || ( x == 'F' ) || ( x == 'G' ) || ( x == 'H' ) || ( x == 'I' ) ||
        ( x == 'J' ) || ( x == 'K' ) || ( x == 'L' ) || ( x == 'M' ) || ( x == 'N' ) || ( x == 'O' ) || ( x == 'P' ) || ( x == 'Q' ) || ( x == 'R' ) || ( x == 'S' ) ||
          ( x == 'T' ) || ( x == 'U' ) || ( x == 'V' ) || ( x == 'W' ) || ( x == 'X' ) || ( x == 'Y' ) || ( x == 'Z' )) {
                  return ( x - 'A' + 13 ) % 26 + 'A';
        } else {
                return ( x );
        }
}

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What happened to isalpha?

And you can make the return statement a little better by adding 13 and then subtracting 26 if isalpha is false again.