Returning value in conditional operator

问题

I was trying to return value true or false depending upon the condition by using a conditional operator but I got an error. Here is my code,

bool isEmpty()
{
    int listSize = Node::size();
    listSize > 0 ? return (true) : return (false);
    return false;
}

And here is the error,

error C2107: illegal index, indirection not allowed

Now I am stuck here. I don't get the point.Logically I think it should be correct. Please guide me about it . Thanks

回答1:

You can only have expressions* as the operands of the ternary conditional, not statements. The usual way to say this is:

return listSize > 0 ? true : false;

or even better,

return listSize > 0;

or even better,

bool isEmpty() { return Node::size() > 0; }

*) Since you tagged this as both C and C++, know that there is a subtle difference between the admissible expressions in the two languages.

回答2:

The ternary operator (?:) is not designed to be used like that. You have a syntax error.

Try this instead:

return (listSize > 0);

回答3:

Unless you have a deeper reason for doing this that I am missing, you should just return (listSize > 0);.

来源：https://stackoverflow.com/questions/7046120/returning-value-in-conditional-operator