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In computer programming, operators are built-in functions similar to mathematical [[operation]]s.  This article focuses primarily on numerical operators and relational operators.  For other types and some special cases, see [[string#String Operations|String operations]], [[boolean#Boolean Operations|Boolean operations]] and [[python sequence types#Sequence Operations|Sequence operations]].

==Numerical Operators==
*<tt>x + y</tt> returns the sum of x and y.  
*<tt>x - y</tt> returns the difference of x and y.
*<tt>x*y</tt> returns the product of x and y.
*<tt>x/y</tt> returns the quotient of x and y.  The result will always be a [[floating point number|float]].
*<tt>x//y</tt> returns the quotient of x and y rounded down to the nearest integer.  This is also known as integer division.  The result will still be a float if one of the inputs was.
*<tt>x%y</tt> is the modulo operation, and returns the remainder when x is divided by y.
*<tt>-x</tt> returns the negation of x.
*<tt>abs(x)</tt> returns the absolute value of x.
*<tt>x**y</tt> and <tt>pow(x,y)</tt> both return <math>x^y</math>.  As is common for programming languages, Python defines <tt>0**0</tt> to be 1, despite the fact that <math>0^0</math> is undefined in many mathematical contexts.

For the operators that take more than one argument, if either of the arguments are [[floating point number|floats]] the output will always be a float (rather than an integer) unless otherwise noted.

==Relational Operators==
Relational operators, also simply called comparisons, are operators that return [[boolean]]s.
*<tt>x < y</tt> returns True [[iff]] x is strictly less than y.
*<tt>x > y</tt> returns True iff x is strictly greater than y.
*<tt>x <= y</tt> returns True iff x is less than or equal to y.
*<tt>x >= y</tt> returns True iff x is greater than or equal to y.
*<tt>x == y</tt> returns True iff x is equal to y.
*<tt>x != y</tt> returns True iff x is not equal to y.
Notes:
#In Python, = is not a relational operator, it's actually the assignment operator.  == is used for equality testing.  
#When comparing [[string]]s to each other Python uses '''lexicographic order''', so one string will be less than another if it would appear earlier in a dictionary.
#It's bad practice to rely on equality testing of [[floating point number]]s.  See the related article for an explanation.

==Precedence Rules==
Python understands and adheres to the standard precedence rules.  In particular, operators will be applied in the following order:
#Terms in parentheses
#Exponentiation
#Negation
#Multiplication and division
#Addition and subtraction
#Comparisons
#Boolean operations (e.g. <tt>and</tt>, <tt>or</tt>, and <tt>not</tt>)
Operators of the same precedence level are applied from left to right.  For more clarity or if you need to override these rules you can enclose subexpressions in parentheses.

==See Also==
[http://docs.python.org/py3k/library/stdtypes.html#comparisons Python 3.2 Documentation]

[[Category:Introduction to Programming]]

[[Category:Computer programming]]