Regarding C# syntax

Tommy Sin

I do not understand the return statement, can anyone explain what ?, : does and explain about the return statement?
Thanks
public IAppTools Get(string appToolName)
{
if (string.IsNullOrEmpty(appToolName))
appToolName = Constants.APP_TOOL_NAME_DEFAULT;
return _appTools.ContainsKey(appToolName) ? _appTools[appToolName] : null;
}

3 Replies

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Guest User15y ago
Accepted answer
That's called the ternary operator. First, it evaluates the expression before the ? -- this expression must evaluate to either true or false. If the expression is true, then the value to the left of the : is returned. If the expression is false, the value to the right of the : is returned.

It's basically another way to do this:

if ( _appTools.ContainsKey(appToolName)) return _appTools[appToolName] else return null;

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Sam Hobbs15y ago
Actually, ternary is the type of operator, since it has three parts. The operator is called the conditional operator.
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Sam Hobbs15y ago
Note also that most of C# syntax is the same as C++. The operator you are asking about is called the Conditional Operator (?: Operator (C# Reference)); see the C++ version Conditional Operator: ? : (C++). It is syntax initially designed for the C language, which was designed without a formal design process. In other words, C was designed by a few (I think three, including Kernigahn and Richie) individuals and they designed it based on their personal preferences. The C# language retains some of those personal preferences. Some of the statements and operators, especially the switch statement, have had minor improvements. The switch statement syntax is nearly the same but I guess the main improvment is semantic, and those improvements can significantly reduce the possibility for programming mistakes.
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