Regarding C# syntax

Question

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;
}

John Penn · 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 ;

Sam Hobbs · Answer

Actually ternary is the type of operator since it has three parts. The operator is called the conditional operator.

Sam Hobbs · Answer

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.