Question

How do I check if a class is null or not in C++? Suppose I have class Line:

Line line[1000];

if (line[0] == NULL)
   cout << "NULL";
else
   cout << "NOT NULL";

I get this error message:

no match for ‘operator=’ in ‘line[i] = 0’

Answer 1

The code

Line line[1000];

creates 1000 Line objects and stores them in the line array. The test against NULL makes no sense. You could define

Line* line[1000];

In that case you need to initialize the array and your test would work.