How to generate random numbers in C two colons?

debugcn Published at Dev

John

I need in c code that generates two numbers in horizontally...so that i can get token numbers for my login system.

I need that i get this:

token=0.152644,0.429187

so in example i have token= and random generated numbers that have at beginning 0. and then 6 random generated numbers separated with , sign. How to get get this in C?

I have try this code but it does not give me what i want_

#include <stdio.h>
#include <string.h>

typedef
union
{
    char tmp[sizeof(unsigned long long)];
    unsigned long long myll;
} ll_t;


unsigned long long llrand(void)
{
    FILE *in=fopen("/dev/urandom", "r");
    ll_t ll_u;
    fread(ll_u.tmp, sizeof(ll_u.tmp), 1, in);
    fclose(in);
    return ll_u.myll;
}

int main()
{
    char tmp1[64]={0x0};
    char working[64]={0x0};
    int i=0;

    for(i=0; i< 1; i++)
    {
        while(strlen(tmp1) < 6)
        {
            sprintf(working, "%lu", llrand() );
            strcat(tmp1, working);
        }
        tmp1[6]=0x0;

        printf("%s\n", tmp1);
        *tmp1=0x0;
     }
    return 0;
 }

From output i get this:

747563
102595

Can code be simple and short?

Viet

You can use rand() function:

#include <stdio.h>      /* printf, scanf, puts, NULL */
#include <stdlib.h>     /* srand, rand */
#include <time.h>       /* time */

int randomNumber(int min, int max)
{
    /* generate secret number between min and max: */
    int res = rand() % (max-min+1) + min;
    return res;
}

int main()
{
    int i = 0;
    srand (time(NULL));
    for (i=0; i<100; i++)
        printf("%d ", randomNumber(10, 1000000));
    return 0;
}

That is full detail for rand(): http://www.cplusplus.com/reference/cstdlib/rand/

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