C# Language Specification

Method body

The method-body of a method declaration consists of either a block or a semicolon.

Abstract and external method declarations do not provide a method implementation, so their method bodies simply consist of a semicolon. For any other method, the method body is a block (§8.2) that contains the statements to execute when that method is invoked.

The result type of a method is void if the return type is void, or if the method is async and the return type is System.Threading.Tasks.Task. Otherwise, the result type of a non-async method is its return type, and the result type of an async method with return type System.Threading.Tasks.Task<T> is T.

When the result type of a method is void, return statements (§8.9.4) in that method’s body are not permitted to specify an expression. If execution of the method body of a void method completes normally (that is, control flows off the end of the method body), that method simply returns to its current caller.

When the result type of a method is not void, each return statement in that method’s body must specify an expression that is implicitly convertible to the result type. The endpoint of the method body of a value-returning method must not be reachable. In other words, in a value-returning method, control is not permitted to flow off the end of the method body.

In the example

class A
{
public int F() {} // Error, return value required

public int G() {

return 1;
}

public int H(bool b) {

if (b) {
return 1;
}
else {
return 0;
}
}
}

the value-returning F method results in a compile-time error because control can flow off the end of the method body. The G and H methods are correct because all possible execution paths end in a return statement that specifies a return value.

11.