Easy to solve problem about rand()

[Aceix]

Why does this give me the same number every time? ie: 3

string fnRandom()
{
    srand(NULL);
    int nTemp;

    nTemp=rand()%9+1;
    if(nTemp==1) {return "A1";}
    if(nTemp==2) {return "B1";}
    if(nTemp==3) {return "C1";}
    if(nTemp==4) {return "A2";}
    if(nTemp==5) {return "B2";}
    if(nTemp==6) {return "C2";}
    if(nTemp==7) {return "A3";}
    if(nTemp==8) {return "B3";}
    if(nTemp==9) {return "C3";}

    return "0";
}

Aceix.

[Chervil]

Because you use the same seed each time.

[Aceix]

Never mind. Problem SOLVED!!!

Soln:
srand(time(NULL));

Thanks for trying to help,
Aceix.

[Disch]

Note you should NOT call srand in this function at all.

You should call srand() exactly once when the program starts. You must not call it every time you generate a new random number.

[Rayquaza4096]

Disch, why do you advise against calling srand() whenever you generate a random number? I am guilty of doing this in many of my programs, and I am curious as to why it is considered bad practice.

[EssGeEich]

1. Because it's a waste of performance.
2. Because it's not needed.
3. Because it's just a risk of non-randomness in certain cases.

So: Just stick with what Disch said, Just call srand() once, unless you need to reproduce a bug (eg if a bug is rand-dependent, in Debug mode you may want to call srand ~once~ with a specific number so you can reproduce and debug the bug) or you don't need complete randomness.

[Rayquaza4096]

Thanks for your help! It makes sense that it is not needed to call srand() too many times.