Question

int i, nhashprime = nextprime(2 * hashprime) ;

Does this line equal

int i, nhashprime;
i = nextprime(2 * hashprime);
nhashprime = i;

or does it do something else?

Answer 1

This initializes nhashprime and not i. The int part applies to both i and nhashprime, but the assignment only applies to nhashprime. The code is equivalent to

int i;
int nhashprime = nextprime(2 * hashprime);

It’s generally not a good idea to combine multiple declarations into one, except in the simple case with simple types and no initialization:

int i, j, k;

Note in particular that pointer markers do not distribute to multiple identifiers either:

int *p, i;

should be avoided and is equivalent to

int *p;
int i;