num = forward.Data.Key >= key ? 1 : 0;

if( forward.Data.Key >= key ) {
    num = 1;
}
else {
    num = 0;
}

value = condition ? truePart : falsePart;

int input = Convert.ToInt32(Console.ReadLine());
string classify;

// if-else construction.
if (input < 0)
    classify = "negative";
else
    classify = "positive";

// ?: conditional operator.
classify = (input < 0) ? "negative" : "positive";