Method Call using Ternary Operator

Question

While playing around with new concepts, I came across the Ternary Operator and its beauty. After playing with it for a while, I decided to test its limits.

However, my fun was ended quickly when I couldn't get a certain line of code to compile.

int a = 5; int b = 10; a == b ? doThis() : doThat()       private void doThis()     {         MessageBox.Show("Did this");     }     private void doThat()     {         MessageBox.Show("Did that");     } 

This line gives me two errors:

Error   1   Only assignment, call, increment, decrement, and new object expressions can be used as a statement Error   2   Type of conditional expression cannot be determined because there is no implicit conversion between 'void' and 'void' 

I have never used a Ternary Operator to decide which method to be called, nor do I know if it is even possible. I just like the idea of a one-line If Else Statement for method calling.

I have done a bit of research and I cannot find any examples of anyone doing this, so I think I might be hoping for something impossible.

If this is possible, please enlighten me in my wrong doings, and it isn't possible, is there another way?

Answer 1

The ternary operator is used to return values and those values must be assigned. Assuming that the methods doThis() and doThat() return values, a simple assignment will fix your problem.

If you want to do what you are trying, it is possible, but the solution isn't pretty.

int a = 5; int b = 10; (a == b ? (Action)doThis : doThat)(); 

This returns an Action delegate which is then invoked by the parenthesis. This is not a typical way to achieve this.

Answer 2

Ternary operator must return something. A typical usage is like this:

int x = (a > b) ? a : b; 

If you try something like

a + b; 

The compiler will complain.

(a > b) ? a - b : b - a; 

is basically a shortcut for either "a - b" or "b - a", which are not legitimate statements on their own.