Declaration of long int*

[calnastic]

Hi, I'm trying to use this piece of code as a random number generator:

float ran0(long *idum)
{
        long k;
        float ans;
        
        *idum ^= MASK;
        k=(*idum)/IQ;
        *idum=IA*(*idum-k*IQ)-IR*k;
        if (*idum < 0) *idum += IM;
        ans=AM*(*idum);
        *idum ^= MASK;
        return ans;
}

which requires passing of a long*.
In my main, I fail to declare a long*. This is what I wrote:

int main()
{
        float rand = 0;
        long *seed = 123;
        rand = ran0(seed);
        cout << "The answer is" << rand ;
        return 0;
}

And the error code is:

ran0.cpp: In function `int main()':
ran0.cpp:30: invalid conversion from `int' to `long int*'

Please advise how to declare it, thank you.

[firedraco]

Read:
http://cplusplus.com/doc/tutorial/pointers/

You won't need a real pointer here.