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C# 5.0 Pocket Reference by Ben Albahari, Joseph Albahari

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Statements

Functions comprise statements that execute sequentially in the textual order in which they appear. A statement block is a series of statements appearing between braces (the {} tokens).

Declaration Statements

A declaration statement declares a new variable, optionally initializing the variable with an expression. A declaration statement ends in a semicolon. You may declare multiple variables of the same type in a comma-separated list. For example:

bool rich = true, famous = false;

A constant declaration is like a variable declaration, except that it cannot be changed after it has been declared, and the initialization must occur with the declaration (more on this in Constants):

const double c = 2.99792458E08;

Local variable scope

The scope of a local variable or local constant variable extends throughout the current block. You cannot declare another local variable with the same name in the current block or in any nested blocks.

Expression Statements

Expression statements are expressions that are also valid statements. In practice, this means expressions that “do” something; in other words, expressions that:

  • Assign or modify a variable

  • Instantiate an object

  • Call a method

Expressions that do none of these are not valid statements:

string s = "foo";
s.Length;          // Illegal statement: does nothing!

When you call a constructor or a method that returns a value, you’re not obliged to use the result. However, unless the constructor or method changes state, the statement is useless:

new StringBuilder(); ...

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