Thread: Is it possible to generate a certain number of random numbers in C?

I got a homework for a class where we're supossed to use Java. But since we just started the teacher let us to use C too if using Java is too difficult. I gave up with Java. So, I wrote in C instead. I know in Java it's possible to generate a number of random numbers, but how about in C? My program is almost complete. The only problem is I don't know how to generate random numbers.

the program is supposed to generate a number of random numbers. So, do I need to use loop like this?

Code:

for(x=0; x<VALUE; x++)
    {
        srand ( time(NULL) );
        arr[x] = rand() % 10 + 1;
        printf("--> %d\n", arr[x]);
    }

Let's say VALUE is 10. So, the program should generate 10 different numbers. But, that wasn't what i got.
Instead, I got something like this.

--> 10
--> 10
--> 10
so on...

or
--> 5
--> 5
--> 5
so on..

It generates the same numbers! I really do not know way. it is the first time I use srand() and rand(). So, please someone tell me the mistake.

One last thing, how do I generate negative numbers?

Thanks in advance

Wow, thank you very much! That really helps. So, I finally changed it into this

Code:

srand ( time(NULL) );
    for(x=0; x<VALUE; x++)
    {
        arr[x] = rand() % 20 * -1 + 10;
        printf("%d\t", arr[x]);
    }

Thanks again, everyone!

Originally Posted by soawperL25

Wow, thank you very much! That really helps. So, I finally changed it into this

Code:

srand ( time(NULL) );
    for(x=0; x<VALUE; x++)
    {
        arr[x] = rand() % 20 * -1 + 10;
        printf("%d\t", arr[x]);
    }

Thanks again, everyone!

I am giving you an additional exercise:

* Explain why moving the srand() outside of the loop changed what is printed; i.e. why did doing this fix the code?

Originally Posted by Hodor

I am giving you an additional exercise:

* Explain why moving the srand() outside of the loop changed what is printed; i.e. why did doing this fix the code?

I guess that is because srand() is the function which generates the time for random the number. So, when I moved it out it generates different number for each loop? Lol, no. Can't really figure it out. So, what is it?