The out keyword causes arguments to be passed by reference.

It is like the ref keyword, except that ref requires that the variable be initialized before it is passed. To use an out parameter, both the method definition and the calling method must explicitly use the out keyword.

The out keyword can also be used with a generic type parameter to specify that the type parameter is covariant. For more information on the use of the out keyword in this context, see out Generic Modifier. Variables passed as out arguments do not have to be initialized before being passed in a method call.

However, the called method is required to assign a value before the method returns. Although the ref and out keywords cause different run-time behavior, they are not considered part of the method signature at compile time. Therefore, methods cannot be overloaded if the only difference is that one method takes a ref argument and the other takes an out argument.

The following code, for example, will not compile:. Overloading is legal, however, if one method takes a ref or out argument and the other uses neither, like this:. For information about passing arrays, see Passing Arrays Using ref and out.

C# in Depth: Overloading

You can't use the ref and out keywords for the following kinds of methods:. Async methods, which you define by using the async modifier. Iterator methods, which include a yield return or yield break statement. Declaring a method with out arguments is useful when you want a method to return multiple values.

Citigroup Inc: NYSE:C quotes & news - Google Finance

The following example uses out to return three variables with comex copper futures trading hours single method call.

Note that the third argument is assigned to binary options recognize trends. This enables methods to return values optionally.

All c# extension methods - Extension Method

The Try pattern involves returning a bool to c# call method with out parameters whether an operation succeeded and failed, and returning the value produced by make money openttd operation in an out c# call method with out parameters. A number of parsing methods, such as the System. DateTime method, use this pattern. In C 6 and earlier, you must declare a variable in a separate statement before you pass it as an out argument.

The following example declares a variable named number before it is passed to the [Int Int32 method, which attempts to convert a string to a number. Starting with C 7, you can declare the out variable in the argument list of the method call, rather than in a separate variable declaration.

This produces more compact, readable code, and also prevents you from inadvertently assigning a value to the variable before the method call. The following example is like the previous example, except that it defines the number variable in the call to the [Int In the previous example, the number variable is strongly typed as an int.

You can also declare an implicitly typed local variable, as the following example does. For more information, see the C Language Specification.

The language specification is the definitive source for C syntax and usage. C Reference C Programming Guide C Keywords Method Parameters. This content is not available in your language but here is the English version. Comments Edit Share Twitter.