Whats wrong with setting nullable double to null?

Question

Possible Duplicates:
Why can't I set a nullable int to null in a ternary if statement?
Nullable types and the ternary operator. Why won't this work?

Whats wrong with the below

public double? Progress { get; set; }
Progress = null; // works
Progress = 1; // works
Progress = (1 == 2) ? 0.0 : null; // fails

Type of conditional expression cannot be determined because there is no implicit conversion between 'double' and '<null>'

dup http://stackoverflow.com/questions/2766932/why-cant-i-set-a-nullable-int-to-null-in-a-ternary-if-statement — pavanred, Nov 22 '10 at 12:57

score 35 · Accepted Answer · edited Jun 14 '18 at 14:42

35

When using the ?: operator, it has to resolve to a single type, or types that has an implicit conversion between them. In your case, it will either return a double or null, and double does not have an implicit conversion to null.

You will see that

Progress = (1 == 2) ? (double?)0.0 : null;

works fine, since there is an implicit conversion between nullable double and null

edited Jun 14 '18 at 14:42

AustinWBryan

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answered Nov 22 '10 at 12:54

Øyvind Bråthen

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score 0 · Answer 2 · answered Nov 22 '10 at 12:57

0

The double is 0.0 in this case

Progress = (1 == 2) ? (double?)0.0 : null; // works

answered Nov 22 '10 at 12:57

Colin Pickard

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Whats wrong with setting nullable double to null?

2 Answers2