为什么当char数据等于对象数据时，Equals（）的计算结果为false？

Question

Consider the following snippet:

char ch = '[';
string d = "[";

Console.WriteLine(ch.Equals(d))

Output will be false .

What do you do when you want it to be true ?

Edit:

variable d is a string in the example, but in practice it can be any object...

Answer 1

使用ToString();

var result = '['.ToString().Equals("[");

Answer 2

What do you do when you want it to be true?

Convert your char ch to string using ch.ToString

Console.WriteLine(ch.ToString().Equals(d));

Or Convert string to char using Convert.ToChar

Console.WriteLine(ch.Equals(Convert.ToChar(d)));

But the above would fail if your string contains more than one character.

EDIT:

variable d is a string in the example, but in practice it can be any object...

Then it would be better to use Convert.ToChar(object) method to convert the object to character and then compare for equality.

string d = "[";
char ch = '[';
object o = (object)d;
Console.WriteLine(ch.Equals(Convert.ToChar(o)));

The above could throw an exception if the object is not convertible to char , to be on the safe side you can use char.TryParse like:

string d = "[";
char ch = '[';
object obj = (object)d;
char temp;
bool result = obj != null && 
              char.TryParse(obj.ToString(), out temp) && 
              ch == temp; //same as ch.Equals(temp);

This would return false, if the conversion to character is not successful.

Answer 3

It depends on what you intend. Either this

Console.WriteLine(ch.Equals(d[0]));

or that

Console.WriteLine(ch.ToString().Equals(d));

If d could be any object (like you added), you could try to use d.ToString() as well. But what sense does it make to compare a char to a slider? Depending on the actual type of the object the comparison could become True accidentally.

Answer 4

More generally:

char ch = '[';
string d = "[";

bool areEqual = (d != null) && (d.Length == 1) && (d[0].Equals(ch));

Assuming you don't want it to be true when comparing null or "[XXX" with '['.