How to use the ternary operator inside an interpolated string?

问题

I\'m confused as to why this code won\'t compile:

var result = $\"{fieldName}{isDescending ? \" desc\" : string.Empty}\";

If I split it up, it works fine:

var desc = isDescending ? \" desc\" : string.Empty;
var result = $\"{fieldName}{desc}\";

回答1:

According to the documentation:

The structure of an interpolated string is as follows:

{ <interpolationExpression>[,<alignment>][:<formatString>] }

The problem is that the colon is used to denote formatting, like:

Console.WriteLine($"The current hour is {hours:hh}")

The solution is to wrap the conditional in parenthesis:

var result = $"Descending {(isDescending ? "yes" : "no")}";

来源：https://stackoverflow.com/questions/31844058/how-to-use-the-ternary-operator-inside-an-interpolated-string