I need a function to generate a random alphanumeric password in C code. It needs to be between 6-8 characters and follow the following rules:

Reject if same char appears # time: 4 or more
Reject if same char appears consecutively: 3 or more

I have the following random password working for numbers (0-9). I need to update it to include characters (a-z). I also need to add the validation rules above. Can someone please help me. I have been trying for days to update it but get a lot of compile errors... Thanks..

Here's what is working for number (0-9):

Random_Password()
{

int ran_int_num;

time_t seconds;
time(&seconds);

srand ((unsigned int) seconds);

/* multiply by 975 to generate a larger number */
ran_int_num = rand() * 975;

/**************************************************/
/* Need to cast the integer to character, so use sprintf */
/* %u = unsigned decimal integer %d = signed decimal integer */
/* ************************************************/

sprintf(randompw, "%u", ran_int_num);
strncpy(newpw, randompw, 8);


return(0);

}



Here's what I tried to change it to, in order to generate an alphanumeric:


GenerateRandomID()

{
char password_chars["1234567890abcdefghijklmnopqrstuvwxyz"];
int i;
int length;
char ticketid;
int random;

for (i = 0; i < length; i++) {
random = rand(0, strlen(password_chars) - 1);
ticketid = password_chars[random];
}
return ticketid;
}

Here is a simple algorithm:

Jim, thank you so much. I've been busy on other hot projects, so won't be able to try in for a couple of days. Thanks again for the very quick response.