The rand function

[SimpleIce]

Hello, everyone.

This is a sample code of my function, which allocate memory for random char array.

#include <stdlib.h>
#include <time.h>
unsigned char * separator_generator(unsigned char * len)
{
    /* Variable declaration */
    unsigned char * separator_pointer;
    time_t t;
    int i;

    /* Generating random length */
    srand((unsigned)time(NULL));
    unsigned char separator_len = rand() % 70 + 20;


    /* Allocating memory for separator */
    separator_pointer = malloc(sizeof(char)*separator_len);

    /* Generating separator */
    for (i=0; i<separator_len; i++)
    {
        separator_pointer[i] = rand()%256;
    }

    *len = separator_len;
    return separator_pointer;
}

I use this function here:

unsigned char * separator_f;
unsigned char * separator_s;
unsigned char separator_f_len;
unsigned char separator_s_len;

separator_f = separator_generator(&separator_f_len);
separator_s = separator_generator(&separator_s_len);

And the problem...

When i compile program and run it in a console
The separator_f and separator_s has the same length and the same content.

WHY????

[Athar]

That's because you seed the PRNG with the same value before generating each set of numbers.
See http://www.cplusplus.com/reference/clibrary/cstdlib/srand/

You should call srand just once at the beginning of your program.

[SimpleIce]

Thanks, Athar.
Already, clear up.