C# Programming/Keywords/out

The out keyword explicitly specifies that a variable should be passed by reference to a method, and set in that method. A variable using this keyword must not be intialized before the method call to ensure the developer understand its intended effects. Using this keyword requires the called method to set the variable using this modifier before returning. Using out also requires the developer to specify the keyword even in the calling code, to ensure that it is easily visible to developers reading the code that the variable will have its value changed elsewhere, which is useful when analyzing the program flow.

An example of passing a variable with out follows:

void CallingMethod()
{
    int i;
    SetDependingOnTime(out i);
    // i is now 10 before/at 12 am, or 20 after
}

void SetDependingOnTime(out int iValue)
{
    iValue = DateTime.Now.Hour <= 12 ? 10 : 20;
}

C# Keywords
abstract as base bool break byte case catch char checked class const continue decimal default delegate do double else enum event explicit extern false finally fixed float for foreach goto if implicit in int interface internal is lock long namespace new null object operator out override params private protected public readonly ref return sbyte sealed short sizeof stackalloc static string struct switch this throw true try typeof uint ulong unchecked unsafe ushort using var virtual void volatile while
Special C# Identifiers (Contextual Keywords)
add alias async await dynamic get global nameof partial remove set value when where yield
Contextual Keywords (Used in Queries)
ascending by descending equals from group in into join let on orderby select where