Question

In C#, when calling some instance methods, We always declare a variable of that type, then assign a value to it, and call that method at last:

string str = "this is a string";
int test = str.IndexOf("a");

In Javascript, we can do this:

var test = 'sdfsldkfjskdf'.indexOf('a');

Is this kind of method calls legal in C#, say, directly use the string literal as a shorthand, without the declaration of a variable?

Answer 1

Yes, it’s absolutely valid and fine.

I suspect you don’t always declare a variable even without using literals. For example, consider:

string x = "hello";
string y = x.Substring(2, 3).Trim();

Here we’re using the result of Substring as the instance on which to call Trim. No separate variable is used.

But this could equally have been written:

string y = "hello".Substring(2, 3).Trim();

The same is true for primitive literals too:

string x = 12.ToString("0000");

Ultimately, a literal is just another kind of expression, which can be used as the target of calls to instance methods.