C# if then else shorthand won't compile

Question

The following compiles ok:

if (_logon.LogonToConnector())
{
    MessageBox.Show("Logon Success");
}
else
{
    MessageBox.Show("Logon Failed");
}

But for the more concise equivalent:

_logon.LogonToConnector() ? MessageBox.Show("Logon Success") : MessageBox.Show("Logon Failure");

The compiler gives the error:

Only assignment, call, increment, decrement, and new object expressions can be used as a statement UniformTestClient

Where did I go wrong?

The ternary operator is used to return values and those values must be assigned. Here is a workaround https://stackoverflow.com/a/38451083/2946329 — Salah Akbari, Jul 18 '18 at 08:55
_Where did I go wrong?..._ `Only assignment, call, increment, decrement, and new object expressions can be used as a statement UniformTestClient` Its all about that — B001ᛦ, Jul 18 '18 at 08:55
Just a single google-search and you would have got the answer far faster then typing in your question. — MakePeaceGreatAgain, Jul 18 '18 at 09:00

Dmitry Bychenko · Accepted Answer · 2018-07-18T08:59:00.567

6

Put it

MessageBox.Show(_logon.LogonToConnector() 
  ? "Logon Success"
  : "Logon Failed");

since ternary operator must return a value.

edited Jul 18 '18 at 08:59

answered Jul 18 '18 at 08:56

Dmitry Bychenko

score 2 · Answer 2 · answered Jul 18 '18 at 08:58

Ternary operator returns a value based on true/false which has to be assigned. You can't shorten your if/else statement this way.

You could do something like

string message = _logon.LogonToConnector() ? "Logon Success" : "Logon failed";

MessageBox.Show(message);

2 Answers2