[muffinman8641]

I'm making a tiny program to familiarize myself with arrays. My code is this:

#include <iostream>
#include <string.h>
#include <time.h>

using namespace std;
void generate();

int rnd(int range);

int main() {
    int x[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, i = 0;
    char y[4] = {'A', 'B', 'C', 'D'};
    
generate();

while (i < 3) {
     void generate();
     i++;
     }
     
     getchar();
     return 0;
     }

    int rnd(int range) {
      int r;
      r = rand() % range;
      return (r);
            }
                
    void generate() {
      int num, letter;
      
      num = rnd(10);
      letter = rnd(4);
      
      cout << letter << num << endl;
      
      srand((unsigned)time(NULL));
                    }

But it generates two numbers (71, for example, when I'm looking for something like B5 or D3) and only does it once when I want three. What am I doing wrong?

This post has been edited by muffinman8641: 29 March 2011 - 07:39 AM

[muffinman8641]

OK, I think it has something to do with lines 32-35, where I declare num and letter as random numbers. How can I make letter the random letter set?

Also, I turned the Y variable in int main into "char y[]= "ABCD";"

This post has been edited by muffinman8641: 29 March 2011 - 07:56 AM

[runfaster]

What you are doing currently is printing out the random numbers generated by rnd(). You need to tell the computer how to apply those numbers.

Something along the lines of:

cout << x[num] << y[letter] << endl; 

To do this, you would need to either make the x and y arrays global or pass them into the generate function.

Also be aware that you'll probably experience an out of bounds exception when you get a 10 or a 4. Arrays have spaces labeled 0-(n-1) for a an array of size n. I could be wrong. I forget exactly how rnd() works.

Edit: fixed a few grammar things

This post has been edited by runfaster: 29 March 2011 - 08:07 AM

[chinchang]

You are displaying two numbers here:

cout << letter << num << endl;

That is why you see 2 numbers. letter is an index for your y array. So you need to do this :

cout << y[letter] << x[num] << endl;

This post has been edited by chinchang: 29 March 2011 - 08:07 AM

[muffinman8641]

Thanks! I have the right combo of letters and numbers now, but it only does one instead of three.

#include <iostream>
#include <string.h>
#include <time.h>

using namespace std;
void generate();

int rnd(int range);

int main() {
    int i = 0;
    system("CLS");
    system("color 0E");
    
generate();

while (i < 3) { 
     void generate();
     i++;
     }
     
     getchar();
     return 0;
     }


    
    
    int rnd(int range) {
      int r;
      r = rand() % range;
      return (r);
            }
                
    void generate() {
      int x[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, num;
      char y[]= "ABCD", letter;
      
      num = rnd(10);
      letter = rnd(4);
      
      cout << y[letter] << x[num] << endl;
      
      srand((unsigned)time(NULL));
                    }

Not a big deal, but I can't see why.

Also, I now decided to expand it a little to make a random password generator (like the ones you get when you make a new account somewhere; 8GX224L6 or something like that). The thing is, if I just keep repeating << x[num] or y[letter], it gives the same one. How can I seed new random number for each character?

This post has been edited by muffinman8641: 29 March 2011 - 04:05 PM

[chinchang]

Line 18:

void generate();

This is not the way you call a function. You are only declaring a function. The only time the generate() function is called is on Line 15. That is why you get only 1 output.

Change Line 18 to:

generate();

And for generating a more random number, you provide a seed value to srand(). See here.

This post has been edited by chinchang: 30 March 2011 - 05:32 AM

[CTphpnwb]

I would only call srand() once and at the beginning of the code. All it does is initialize the random number seed, and there's no need to do that repeatedly.