function problem in password generator

[Simple Simon]

Just thought I'd suggest the following:

By lepricaun

void generate_password(length)
{
    int length;
    srand(time(NULL));    
    while (length>0)
    {
        
        int cha;
        cha=rand()%128;
        if((cha>=48 && cha<=57) || (cha>=65 && cha<=90) || (cha>=97 && cha<=122))
        {
           printf("%c",cha);
           length--;
        }
    }
}

Yes this works, however, should you be declaring the cha variable every time you loop round in the while loop? It's not efficient. 9/10 from me, especially as you didn't do that in the code this superceeded! LOL

[lepricaun]

yes, your right, but sorry mate, you're a little behind...

this is an old thread, and old code too

here's the final version of the password generator:
pwgenCL_2

/*
pwgenCL version 2 (pwgenCL_2)Copyright (C) 2004 Scorpius, password generator, 
written as a command line scripting utility.
this program is freesource, which means you may use and/or modify it under the GPL license.
if you'd like to contact me with comments/bugs/suggestions or just to say hello,
my email address is: [email protected].
  
i hope you enjoy using my program and that you find it usefull :)         
  
to compile it under windows, get a copy of Dev-C++ (it's free), or another C/C++ compiler.
to compile it under linux, just type "gcc -o pwgenCL_2 pwgenCL_2.c" (without the " quotes)
*/

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <strings.h>

char *generated_password(char*, int,int);

int main(int argc, char** argv)
{   /*the character sets*/
    char *very_easy_set = "abcdefghijklmnopqrstuvwxyz";
    char *very_easy2_set = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    char *easy_set = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    char *medium_set = "abcdefghijklmnopqrstuvwxyz0123456789";
    char *hard_set = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    char *hard2_set = "\\][^_abcdefghijklmnopqrstuvwxyz0123456789";
    char *very_hard_set = "!\"#$%'(*)+,-./abcdefghijklmnopqrstuvwxyz0123456789";
    char *extreme_set = "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~";
    
    int characterset=0;
    int password_length=0;
    int user_supplied=0;
    if(argc!=4)
    {
	    printf("\npwgenCL_2,commandline password generator, Copyright (C) 2004 Scorpius");
    	printf("\n\npwgenCL_2 is free software; you can redistribute it and/or modify");
    	printf("\nit under the terms of the GNU General Public License as published by");
    	printf("\nthe Free Software Foundation; either version 2 of the License.");
    	printf("\n\npwgenCL_2 is distributed in the hope that it will be useful,");
    	printf("\nbut WITHOUT ANY WARRANTY; without even the implied warranty of");
    	printf("\nMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the");
    	printf("\nGNU General Public License for more details.");
    	printf("\n\nYou should have received a copy of the GNU General Public License");
    	printf("\nalong with this program; if not, write to the Free Software");
    	printf("\nFoundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\n");
    	printf("\n\t   ***Contact Scorpius: [email protected]***");
    	printf("\n\nCharacter sets:");
    	printf("\n1: (a-z)\t\t\t\t\tvery easy password");
        printf("\n2: (A-Z)\t\t\t\t\tvery easy password");
        printf("\n3: (a-z,A-Z)\t\t\t\t\teasy password");
        printf("\n4: (a-z,0-9)\t\t\t\t\tmedium password");
        printf("\n5: (A-Z,a-z,0-9)\t\t\t\thard password");
        printf("\n6: (a-z,0-9, \\ ] [ ^ _ )\t\t\thard password");
        printf("\n7: ( ! \" # $ % ' ( * ) + , - . /  ,a-z,0-9)\tvery hard password");
        printf("\n8: full keyboard characters (except space), almost impossible to crack\n\n");
        printf("The maximum password length is 256 characters\n");
        printf("Usage: %s <characterset> <password length> <user supplied number>\n",argv[0]);
        printf("\n*The <user supplied number> is inserted to create extra randomness*\n");
        printf("\nExample: %s 8 15 5454303\n",argv[0]);
        return 0;
    }
    if(argc==4)/*if all parameters, (characterset,passwordlength,randomization number) run the program*/
    {
    	characterset=atoi(argv[1]);/*create integer from the argument*/
    	password_length=atoi(argv[2]);/*create integer from the argument*/
    	user_supplied=atoi(argv[3]);/*create integer from the argument*/
    	if (password_length<1)
        {
		printf("Password length: %d is too small.\n",password_length);
		return EXIT_FAILURE;
		}
		if (password_length>256)
		{
		printf("Password length: %d is too large.\n",password_length);
		return EXIT_FAILURE;
		}
    	switch(characterset)
    	{
                case 1:
                        generated_password(very_easy_set,password_length,user_supplied);
                        break;
                case 2:
                        generated_password(very_easy2_set,password_length,user_supplied);
                        break;
                case 3:
                        generated_password(easy_set,password_length,user_supplied);
                        break;
                case 4:
                        generated_password(medium_set,password_length,user_supplied);
                        break;
                case 5: 
                        generated_password(hard_set,password_length,user_supplied);
                        break;
                case 6:
                        generated_password(hard2_set,password_length,user_supplied);
                        break;
                case 7:
                        generated_password(very_hard_set,password_length,user_supplied);
                        break;
                case 8:
                        generated_password(extreme_set,password_length,user_supplied);
                        break;
               default:
                        printf("Invalid character set\n");
			            return EXIT_FAILURE;
                        break;
    	}
	    return EXIT_SUCCESS;
    }   
    else return EXIT_FAILURE;  
}

/*the password generator function*/

char *generated_password(char* char_set, int length,int user_number)
{
        
        srand(user_number*time(NULL));
        int loop;
        int set_length=strlen(char_set);
    
        for(loop=0;loop<length;loop++)
        {
             putchar(char_set[rand()%set_length]);
        }
        printf("\n");
}

and as you can see, the declaration of the variable isn't done in the loop anymore

for more info on this program check this thread.