Concatenate nullable object with string

Question

This:

int? temp = 0;
return "123 " + temp ?? "null" + " 456";

returns 123 0, but I expected: 123 0 456

This:

int? temp = null;
return "123 " + temp ?? "null" + " 456";

returns 123 , but I expected: 123 null 456

How can I get expected results?

`return "123 " + (temp ?? "null") + " 456";`, please note `(...)`. Your current code does `return "123 " + temp ?? ("null" + " 456");` — Dmitry Bychenko, Aug 27 '20 at 10:25
Does this answer your question? [What is the operator precedence of C# null-coalescing (??) operator?](https://stackoverflow.com/questions/511093/what-is-the-operator-precedence-of-c-sharp-null-coalescing-operator) — GSerg, Aug 27 '20 at 10:26

score 0 · Answer 1 · answered Aug 27 '20 at 10:29

0

You need to change the precedence of the ?? operator. Use

return "123 " + (temp?.ToString() ?? "null") + " 456";

answered Aug 27 '20 at 10:29

adjan

score 0 · Answer 2 · answered Aug 27 '20 at 10:30

Your current code does

  int? temp = 0;
  return "123 " + temp ?? ("null" + " 456");

Put it in different order:

  int? temp = 0;
  return "123 " + (temp?.ToString() ?? "null") + " 456";

Or, in order to get rid of pesky +:

  return $"123 {temp?.ToString() ?? "null"} 456";

score 0 · Answer 3 · answered Aug 27 '20 at 10:30

0

So many fancy solutions here already, I'll add a simple "old stylish one" :)

"123 " + (temp.HasValue ? temp.ToString() : "null") + " 456"

answered Aug 27 '20 at 10:30

Esko

score 0 · Answer 4 · answered Aug 27 '20 at 10:36

0

This is one way of writing it that should work:

$"123 {(temp == null ? "null" : temp.ToString())} 456"

answered Aug 27 '20 at 10:36

Petter

4 Answers4