Operators (C# Programming Guide)
In C#, an operator is a program element that is applied to one or more operands in an expression or statement. Operators that take one operand, such as the increment operator (++) or new, are referred to as unary operators. Operators that take two operands, such as arithmetic operators (+,,*,/), are referred to as binary operators. One operator, the conditional operator (?:), takes three operands and is the sole ternary operator in C#.
The following C# statement contains a single unary operator and a single operand. The increment operator, ++, modifies the value of the operand y.
y++;
The following C# statement contains two binary operators, each with two operands. The assignment operator, =, has the integer variable y and the expression 2 + 3 as operands. The expression 2 + 3 itself consists of the addition operator and two operands, 2 and 3.
y = 2 + 3;
Operators, Evaluation, and Operator Precedence
An operand can be a valid expression of any size, and it can be composed of any number of other expressions. In an expression that contains multiple operators, the order in which the operators are applied is determined by operator precedence, associativity, and parentheses.
Each operator has a defined precedence. In an expression that contains multiple operators that have different precedence levels, the precedence of the operators determines the order in which the operators are evaluated. For example, the following statement assigns 3 to n1.
n1 = 11  2 * 4;
The multiplication is executed first because multiplication takes precedence over subtraction.
The following table separates the operators into categories based on the type of operation they perform. The categories are listed in order of precedence.
Primary Operators
Expression 
Description 

x.y 
Member access 
f(x) 
Method and delegate invocation 
a[x] 
Array and indexer access 
x++ 
Postincrement 
x 
Postdecrement 
new T(...) 
Object and delegate creation 
new T(...){...} 
Object creation with initializer. See Object and Collection Initializers (C# Programming Guide). 
new {...} 
Anonymous object initializer. See Anonymous Types (C# Programming Guide). 
new T[...] 
Array creation. See Arrays (C# Programming Guide). 
typeof(T) 
Obtain System.Type object for T 
checked(x) 
Evaluate expression in checked context 
unchecked(x) 
Evaluate expression in unchecked context 
default (T) 
Obtain default value of type T 
delegate {} 
Anonymous function (anonymous method) 
Unary Operators
Expression 
Description 

+x 
Identity 
x 
Negation 
!x 
Logical negation 
~x 
Bitwise negation 
++x 
Preincrement 
x 
Predecrement 
(T)x 
Explicitly convert x to type T 
Multiplicative Operators
Expression 
Description 

Multiplication 

Division 

Remainder 
Additive Operators
Expression 
Description 

x + y 
Addition, string concatenation, delegate combination 
x  y 
Subtraction, delegate removal 
Shift Operators
Expression 
Description 

x << y 
Shift left 
x >> y 
Shift right 
Relational and Type Operators
Expression 
Description 

x < y 
Less than 
x > y 
Greater than 
x <= y 
Less than or equal 
x >= y 
Greater than or equal 
x is T 
Return true if x is a T, false otherwise 
x as T 
Return x typed as T, or null if x is not a T 
Equality Operators
Expression 
Description 

x == y 
Equal 
x != y 
Not equal 
Assignment and Anonymous Operators
Expression 
Description 

Assignment 

x op= y 
Compound assignment, supports these operators: +=, =, *=, /=, %=, &=, =, !=, <<=, >>= 
(T x) => y 
Anonymous function (lambda expression) 
Logical, Conditional, and Null Operators
Category 
Expression 
Description 

Logical AND 
x & y 
Integer bitwise AND, Boolean logical AND 
Logical XOR 
x ^ y 
Integer bitwise XOR, boolean logical XOR 
Logical OR 
x  y 
Integer bitwise OR, boolean logical OR 
Conditional AND 
x && y 
Evaluates y only if x is true 
Conditional OR 
x  y 
Evaluates y only if x is false 
Null coalescing 
X ?? y 
Evaluates to y if x is null, to x otherwise 
Conditional 
x ?: y : z 
Evaluates to y if x is true, z if x is false 
Associativity
When two or more operators that have the same precedence are present in an expression, they are evaluated based on associativity. Leftassociative operators are evaluated in order from left to right. For example, x * y / z is evaluated as (x * y) / z. Rightassociative operators are evaluated in order from right to left. For example, the assignment operator is right associative. If it were not, the following code would result in an error.
int a, b, c;
c = 1;
// The following two lines are equivalent.
a = b = c;
a = (b = c);
// The following line, which forces left associativity, causes an error.
//(a = b) = c;
The assignment operators and the ternary operator (?:) are right associative. All other binary operators are left associative.
Whether the operators in an expression are left associative or right associative, the operands of each expression are evaluated first, from left to right. The following examples illustrate the order of evaluation of operators and operands.
Statement 
Order of evaluation 

a = b 
a, b, = 
a = b + c 
a, b, c, +, = 
a = b + c * d 
a, b, c, d, *, +, = 
a = b * c + d 
a, b, c, *, d, +, = 
a = b  c + d 
a, b, c, , d, +, = 
a += b = c 
a, b, c, =, += 
Adding Parentheses
You can change the order imposed by operator precedence and associativity by using parentheses. For example, 2 + 3 * 2 ordinarily evaluates to 8, because multiplicative operators take precedence over additive operators. However, if you write the expression as (2 + 3) * 2, the addition is evaluated before the multiplication, and the result is 10. The following examples illustrate the order of evaluation in parenthesized expressions. As in previous examples, the operands are evaluated before the operator is applied.
Statement 
Order of evaluation 

a = (b + c) * d 
a, b, c, +, d, *, = 
a = b  (c + d) 
a, b, c, d, +, , = 
a = (b + c) * (d  e) 
a, b, c, +, d, e, , *, = 
Operator Overloading
You can change the behavior of operators for custom classes and structs. This process is referred to as operator overloading. For more information, see Overloadable Operators (C# Programming Guide).
Related Sections
For more information, see Operator Keywords (C# Reference) and C# Operators.
See Also
Concepts
Reference
Statements, Expressions, and Operators (C# Programming Guide)
Change History
Date 
History 
Reason 

May 2010 
Reviewed the topic for clarity and accuracy. 
Customer feedback. 
July 2008 
Removed erroneous statement about undefined output. 
Information enhancement. 