我已经多次遇到这个问题，虽然答案很有意义，但我想自己用一个简单的控制台应用程序来检查一下。
class Program
{
static void Main(string[] args)
{
// Case 1 : FOR REFERENCE TYPES where class b is a copy of class a
Class1 a = new Class1("Hello");
Class1 b = a;
Console.WriteLine("case 1");
Console.WriteLine(a.GetHashCode());
Console.WriteLine(b.GetHashCode());
Console.WriteLine(a==b); //true
Console.WriteLine(a.Equals(b)); //true
// Case 2 : FOR REFERENCE TYPES where class b is not a copy of class a, but it assigned the same values
// Though the referenced memory addresses are different, the fields of the class are assigned the same values, but will have different hashcodes and are therfore not equal.
Class1 c = new Class1("Hello");
Console.WriteLine(" ");
Console.WriteLine("case 2");
Console.WriteLine(a.GetHashCode());
Console.WriteLine(c.GetHashCode());
Console.WriteLine(a==c);//false
Console.WriteLine(a.Equals(c));//false
// Case 3 : FOR REFERENCE TYPES where two strings are assigned the same values, an exception to the way value types behave.
// using the '==' operstor with strings compares their values not memory addresses.
string s1 = "hi";
string s2 = "hi";
Console.WriteLine(" ");
Console.WriteLine("case 3");
Console.WriteLine(s1 == s2);//true
Console.WriteLine(s1.Equals(s2));//true
//Case 4 : FOR VALUE TYPES - they are the same when comparing the same type.
int x = 5;
int y = 5;
Console.WriteLine(" ");
Console.WriteLine("case 4");
Console.WriteLine(x);
Console.WriteLine(y);
Console.WriteLine(x == y);//true
Console.WriteLine(x.Equals(y));//true
// Case 5 : Another value type scenario for completeness
x = y;
Console.WriteLine(" ");
Console.WriteLine("case 5");
Console.WriteLine(x);
Console.WriteLine(y);
Console.WriteLine(x.GetType());
Console.WriteLine(y.GetType());
Console.WriteLine(x == y);//true
Console.WriteLine(x.Equals(y));//true
// Case 6 : Yet Another value type scenario for completeness, with different value types.
float z = 5;
Console.WriteLine(" ");
Console.WriteLine("case 6");
Console.WriteLine(x.GetType());
Console.WriteLine(z.GetType());
Console.WriteLine(x);
Console.WriteLine(z);
Console.WriteLine(x == z);//true
Console.WriteLine(x.Equals(z));//false, as the values being compared are of two different types- int and float. The .Equals method expects them to be the same type.
// Case 7 : For giggles, Yet Another ref type scenario for completeness, with objects.
string s3 = new string(new char[] { 'h', 'e', 'l', 'l', 'o' });
string s4 = new string(new char[] { 'h', 'e', 'l', 'l', 'o' });
object obj1 = s3;
object obj2 = s4;
Console.WriteLine(" ");
Console.WriteLine("case 7");
Console.WriteLine(obj1.ToString());
Console.WriteLine(obj2.ToString());
Console.WriteLine(obj1.GetHashCode());
Console.WriteLine(obj2.GetHashCode());
Console.WriteLine(obj1 == obj2);//false - as they refer to different addresses.
Console.WriteLine(obj1.Equals(obj2));//true - in this case both objects have the same hashcode.
Console.ReadKey();
}
public class Class1
{
string name;
public Class1(string strName)
{
name = strName;
}
}
}
假设 1：我从通常发布的回复中了解到，对于引用类型， a==b 比较引用，而 a.Equals(b) 比较引用的实际值。这就是在查看我的程序结果时让我感到震惊的原因。
参考我的程序，在案例 2 中 - 虽然 a 和 c 的引用内存地址不同，但它们的字段被分配了相同的值。仍然 a.Equals(c) 返回 false 因为它们仍然不相等，因为它们具有不同的哈希码。我曾假设它们最初会根据假设 1 返回 true，但它们并不相等是有道理的。但是，== 和 .Equals 之间的确切区别究竟是什么？
在情况 3 中，使用带有字符串的 '==' 运算符比较它们的值而不是内存地址。
在案例 6 中，由 .Equals 方法比较的值类型是不同的，而该方法期望它们是相同的类型。因此它返回false。
我仍然不明白的是案例 7。为什么在这种情况下对象具有相同的哈希码？抱歉，代码冗长，提前致谢！