#510 – Declaring More than One Local Variable On the Same Line

You typically declare a local variable by specifying its type, the name of the local variable and an optional initial value.

int j;
int i = 42;

You can declare more than one variable on the same line, as long as the variables all have the same type.  Each variable can optionally include an initialization.

int j, i = 42;      // Only i is assigned
string name = "Sean", motto = "Carpe Libri";
Dog d1, d2, d3;
Dog kirby = new Dog("Kirby", 12), jack = new Dog("Jack", 14);
dynamic thing1, thing2;

You can’t, however, declare multiple implicitly-typed variables on the same line.

            var i = 12, s = "Sean";   // Error: Implicitly-typed local variables cannot have multiple declarators

#341 – Defining and Using Local Variables

You can define variables within a method.  These are known as local variables.  The variables’ values can be read and written while the body of the method is executing.

The Dog.Bark method below defines two local variables–formalName and barkPhrase.

    public class Dog
        public string Name { get; set; }
        public string BarkSound { get; set; }

        public void Bark()
            string formalName = string.Format("Sir {0}", Name);
            string barkPhrase = string.Format("{0} {0}!", BarkSound);

            Console.WriteLine("{0} says {1}", formalName, barkPhrase);

Local variables can be initialized when they are declared, or they can be set to a value later.  Since C# requires definite assignment, they must be given a value before they are read.