ECMA-334 C# Language Specification

15.5.1: Local variable declarations

A local-variable-declaration declares one or more local variables.

local-variable-declaration
type local-variable-declarators
local-variable-declarator
local-variable-declarator
local-variable-declarators , local-variable-declarator
local-variable-declarator
identifier
identifier = local-variable-initializer
local-variable-initializer
expression
array-initializer

The type of a local-variable-declaration specifies the type of the variables introduced by the declaration.

The type is followed by a list of local-variable-declarators, each of which introduces a new variable. A local-variable-declarator consists of an identifier that names the variable, optionally followed by an "=" token and a local-variable-initializer that gives the initial value of the variable.

The value of a local variable is obtained in an expression using a simple-name (14.5.2), and the value of a local variable is modified using an assignment (14.13). A local variable must be definitely assigned (12.3) at each location where its value is obtained.

The scope of a local variable declared in a local-variable-declaration is the block in which the declaration occurs. It is an error to refer to a local variable in a textual position that precedes the local-variable-declarator of the local variable. Within the scope of a local variable, it is a compile-time error to declare another local variable or constant with the same name.

A local variable declaration that declares multiple variables is equivalent to multiple declarations of single variables with the same type. Furthermore, a variable initializer in a local variable declaration corresponds exactly to an assignment statement that is inserted immediately after the declaration.

[Example: The example
void F() {  
   int x = 1, y, z = x * 2;  
}  
corresponds exactly to
void F() {  
   int x; x = 1;  
   int y;  
   int z; z = x * 2;  
}  
end example]