Any help on making random char code?

I need to create a random code that uses "abcde" and that does not repeat any letters, but I have no idea how to do that, I know how to make random numbers, but not chars, any help?
This is what I need them for:

Code:

---

#include <iostream>
#include <cstring>
#include <ctime>
using namespace std;

int main()
{

        char code[6] = "abcde";  // here I want the ranom code
        char icode[6];
        char letter;
        char opcion;

        bool playagain = false;

        int i = 0;
        int correct = 0;

        do
        {
                cout << "\t\t*RULES*\n\n";
                cout << "1.- You do NOT speak about Fight Club.... lol.\n";
                cout << "2.- You do NOT write in CAPS.\n";
                cout << "3.- You do NOT write more than 5 lettrrs per guess.\n\n\n";
                cout << "Try to guess a code I have thought of:\n";
                do
                {
                        icode[5] = '\0';

                        for (i = 0; i < 5; i++)
                        {
                                cin >> letter;

                                icode[i] = letter;

                                if (icode[i] == code[i])
                                {
                                        correct++;
                                }
                        }
                        cout << "You had " << correct << " correct letters!\n";

                        if (!strcmp(code, icode))
                        {
                                cout << "You guessed the code!\n";
                        }
                        correct = 0;

                } while (strcmp(code, icode));

                cout << "Do you want to play again? (y/n)\n";
                cin >> opcion;
                playagain = (opcion == 'y' ? true : false);

        } while (playagain);

        return 0;
}

---

Random characters are the same as random numbers, you just have to specify a starting number:

A - Z : 65 - 90
a - z : 97 - 122

Example:
Random letter A, B or C

((rand() % 3) + 65)

Random letter d, e, f, g or h

((rand() % 5) + 97 + 3)


The problem will be not to repeat any letters. You could generate a letter, check if it is already picked (storing the picked one in an array) and if it already exists, pick a new one.

Another solution would be to place all available letters in an array, then do random swaps several times to get them in a random order (generate two random indices, then swap the letters at those two positions in the array).