Operators are the constructs which can manipulate the value of operands.
Consider the expression 4 + 5 = 9. Here, 4 and 5 are called operands and + is called operator.
Types of Operator
Python language supports the following types of operators.
- Arithmetic Operators
- Comparison (Relational) Operators
- Assignment Operators
- Logical Operators
- Bitwise Operators
- Membership Operators
- Identity Operators
Let us have a look on all operators one by one.
Python Arithmetic Operators
Assume variable a holds 10 and variable b holds 20, then
| Operator | Description | Example |
|---|---|---|
| + Addition | Adds values on either side of the operator. | a + b = 30 |
| - Subtraction | Subtracts right hand operand from left hand operand. | a – b = -10 |
| * Multiplication | Multiplies values on either side of the operator | a * b = 200 |
| / Division | Divides left hand operand by right hand operand | b / a = 2 |
| % Modulus | Divides left hand operand by right hand operand and returns remainder | b % a = 0 |
| ** Exponent | Performs exponential (power) calculation on operators | a**b =10 to the power 20 |
| // | Floor Division - The division of operands where the result is the quotient in which the digits after the decimal point are removed.But if one of the operands is negative, the result is floored, i.e., rounded away from zero (towards negative infinity): | 9//2 = 4 and 9.0//2.0 = 4.0, -11//3 = -4, -11.0//3 = -4.0 |
Example
Assume variable a holds 10 and variable b holds 20, then −
#!/usr/bin/python3 a = 21 b = 10 c = 0 c = a + b print ("Line 1 - Value of c is ", c) c = a - b print ("Line 2 - Value of c is ", c ) c = a * b print ("Line 3 - Value of c is ", c) c = a / b print ("Line 4 - Value of c is ", c ) c = a % b print ("Line 5 - Value of c is ", c) a = 2 b = 3 c = a**b print ("Line 6 - Value of c is ", c) a = 10 b = 5 c = a//b print ("Line 7 - Value of c is ", c)
When you execute the above program, it produces the following result −
Line 1 - Value of c is 31 Line 2 - Value of c is 11 Line 3 - Value of c is 210 Line 4 - Value of c is 2.1 Line 5 - Value of c is 1 Line 6 - Value of c is 8 Line 7 - Value of c is 2
Python Comparison Operators
These operators compare the values on either sides of them and decide the relation among them. They are also called Relational operators.
Assume variable a holds 10 and variable b holds 20, then −
| Operator | Description | Example |
|---|---|---|
| == | If the values of two operands are equal, then the condition becomes true. | (a == b) is not true. |
| != | If values of two operands are not equal, then condition becomes true. | |
| <> | If values of two operands are not equal, then condition becomes true. | (a <> b) is true. This is similar to != operator. |
| > | If the value of left operand is greater than the value of right operand, then condition becomes true. | (a > b) is not true. |
| < | If the value of left operand is less than the value of right operand, then condition becomes true. | (a < b) is true. |
| >= | If the value of left operand is greater than or equal to the value of right operand, then condition becomes true. | (a >= b) is not true. |
| <= | If the value of left operand is less than or equal to the value of right operand, then condition becomes true. | (a <= b) is true. |
Example
Assume variable a holds 10 and variable b holds 20, then −
#!/usr/bin/python3 a = 21 b = 10 if ( a == b ): print ("Line 1 - a is equal to b") else: print ("Line 1 - a is not equal to b") if ( a != b ): print ("Line 2 - a is not equal to b") else: print ("Line 2 - a is equal to b") if ( a < b ): print ("Line 3 - a is less than b" ) else: print ("Line 3 - a is not less than b") if ( a > b ): print ("Line 4 - a is greater than b") else: print ("Line 4 - a is not greater than b") a,b=b,a #values of a and b swapped. a becomes 10, b becomes 21 if ( a <= b ): print ("Line 5 - a is either less than or equal to b") else: print ("Line 5 - a is neither less than nor equal to b") if ( b >= a ): print ("Line 6 - b is either greater than or equal to b") else: print ("Line 6 - b is neither greater than nor equal to b")
When you execute the above program it produces the following result −
Line 1 - a is not equal to b Line 2 - a is not equal to b Line 3 - a is not less than b Line 4 - a is greater than b Line 5 - a is either less than or equal to b Line 6 - b is either greater than or equal to b
Python Assignment Operators
Assume variable a holds 10 and variable b holds 20, then
| Operator | Description | Example |
|---|---|---|
| = | Assigns values from right side operands to left side operand | c = a + b assigns value of a + b into c |
| += Add AND | It adds right operand to the left operand and assign the result to left operand | c += a is equivalent to c = c + a |
| -= Subtract AND | It subtracts right operand from the left operand and assign the result to left operand | c -= a is equivalent to c = c - a |
| *= Multiply AND | It multiplies right operand with the left operand and assign the result to left operand | c *= a is equivalent to c = c * a |
| /= Divide AND | It divides left operand with the right operand and assign the result to left operand | c /= a is equivalent to c = c / ac /= a is equivalent to c = c / a |
| %= Modulus AND | It takes modulus using two operands and assign the result to left operand | c %= a is equivalent to c = c % a |
| **= Exponent AND | Performs exponential (power) calculation on operators and assign value to the left operand | c **= a is equivalent to c = c ** a |
| //= Floor Division | It performs floor division on operators and assign value to the left operand | c //= a is equivalent to c = c // a |
Example
Assume variable a holds 10 and variable b holds 20, then −
#!/usr/bin/python3 a = 21 b = 10 c = 0 c = a + b print ("Line 1 - Value of c is ", c) c += a print ("Line 2 - Value of c is ", c ) c *= a print ("Line 3 - Value of c is ", c ) c /= a print ("Line 4 - Value of c is ", c ) c = 2 c %= a print ("Line 5 - Value of c is ", c) c **= a print ("Line 6 - Value of c is ", c) c //= a print ("Line 7 - Value of c is ", c)
When you execute the above program, it produces the following result −
Line 1 - Value of c is 31 Line 2 - Value of c is 52 Line 3 - Value of c is 1092 Line 4 - Value of c is 52.0 Line 5 - Value of c is 2 Line 6 - Value of c is 2097152 Line 7 - Value of c is 99864
Python Bitwise Operators
There are following Bitwise operators supported by Python language
| Operator | Description | Example |
|---|---|---|
| & Binary AND | Operator copies a bit to the result if it exists in both operands | (a & b) (means 0000 1100) |
| | Binary OR | It copies a bit if it exists in either operand. | (a | b) = 61 (means 0011 1101) |
| ^ Binary XOR | It copies the bit if it is set in one operand but not both. | (a ^ b) = 49 (means 0011 0001) |
| ~ Binary Ones Complement | It is unary and has the effect of 'flipping' bits. | (~a ) = -61 (means 1100 0011 in 2's complement form due to a signed binary number. |
| << Binary Left Shift | The left operands value is moved left by the number of bits specified by the right operand. | a << = 240 (means 1111 0000) |
| >> Binary Right Shift | The left operands value is moved right by the number of bits specified by the right operand. | a >> = 15 (means 0000 1111) |
Example
#!/usr/bin/python3 a = 60 # 60 = 0011 1100 b = 13 # 13 = 0000 1101 print ('a=',a,':',bin(a),'b=',b,':',bin(b)) c = 0 c = a & b; # 12 = 0000 1100 print ("result of AND is ", c,':',bin(c)) c = a | b; # 61 = 0011 1101 print ("result of OR is ", c,':',bin(c)) c = a ^ b; # 49 = 0011 0001 print ("result of EXOR is ", c,':',bin(c)) c = ~a; # -61 = 1100 0011 print ("result of COMPLEMENT is ", c,':',bin(c)) c = a << 2; # 240 = 1111 0000 print ("result of LEFT SHIFT is ", c,':',bin(c)) c = a >> 2; # 15 = 0000 1111 print ("result of RIGHT SHIFT is ", c,':',bin(c))
When you execute the above program it produces the following result −
a= 60 : 0b111100 b= 13 : 0b1101 result of AND is 12 : 0b1100 result of OR is 61 : 0b111101 result of EXOR is 49 : 0b110001 result of COMPLEMENT is -61 : -0b111101 result of LEFT SHIFT is 240 : 0b11110000 result of RIGHT SHIFT is 15 : 0b111
Python Logical Operators
There are following logical operators supported by Python language. Assume variable a holds True and variable b holds False then
| Operator | Description | Example |
|---|---|---|
| and Logical AND | If both the operands are true then condition becomes true. | (a and b) is False. |
| or Logical OR | If any of the two operands are non-zero then condition becomes true. | (a or b) is True. |
| not Logical NOT | Used to reverse the logical state of its operand. | Not(a and b) is True. |
Python Membership Operators
Python’s membership operators test for membership in a sequence, such as strings, lists, or tuples. There are two membership operators as explained below
| Operator | Description | Example |
|---|---|---|
| in | Evaluates to true if it finds a variable in the specified sequence and false otherwise. | x in y, here in results in a 1 if x is a member of sequence y. |
| not in | Evaluates to true if it does not finds a variable in the specified sequence and false otherwise. | x not in y, here not in results in a 1 if x is not a member of sequence y. |
Example
#!/usr/bin/python3 a = 10 b = 20 list = [1, 2, 3, 4, 5 ] if ( a in list ): print ("Line 1 - a is available in the given list") else: print ("Line 1 - a is not available in the given list") if ( b not in list ): print ("Line 2 - b is not available in the given list") else: print ("Line 2 - b is available in the given list") c=b/a if ( c in list ): print ("Line 3 - a is available in the given list") else: print ("Line 3 - a is not available in the given list")
When you execute the above program it produces the following result:
Line 1 - a is not available in the given list Line 2 - b is not available in the given list Line 3 - a is available in the given list
Python Identity Operators
Python built-in function id() returns a unique integer as identity of object. Identity operators compare the memory locations of two objects. There are two Identity operators as explained below
| Operator | Description | Example |
|---|---|---|
| is | Evaluates to true if the variables on either side of the operator point to the same object and false otherwise. | x is y, here is results in 1 if id(x) equals id(y). |
| is not | Evaluates to false if the variables on either side of the operator point to the same object and true otherwise. | x is not y, here is not results in 1 if id(x) is not equal to id(y). |
Example
#!/usr/bin/python3 a = 20 b = 20 print ('Line 1','a=',a,':',id(a), 'b=',b,':',id(b)) if ( a is b ): print ("Line 2 - a and b have same identity") else: print ("Line 2 - a and b do not have same identity") if ( id(a) == id(b) ): print ("Line 3 - a and b have same identity") else: print ("Line 3 - a and b do not have same identity") b = 30 print ('Line 4','a=',a,':',id(a), 'b=',b,':',id(b)) if ( a is not b ): print ("Line 5 - a and b do not have same identity") else: print ("Line 5 - a and b have same identity")
When you execute the above program it produces the following result −
Line 1 a= 20 : 1594701888 b= 20 : 1594701888 Line 2 - a and b have same identity Line 3 - a and b have same identity Line 4 a= 20 : 1594701888 b= 30 : 1594702048 Line 5 - a and b do not have same identity
Python Operators Precedence
The following table lists all operators from highest precedence to lowest.
| Operator | Description |
|---|---|
| ** | Exponentiation (raise to the power) |
| ~ + - | Ccomplement, unary plus and minus (method names for the last two are +@ and -@) |
| * / % // | Multiply, divide, modulo and floor division |
| + - | Addition and subtraction |
| >> << | Right and left bitwise shift |
| & | Bitwise 'AND'td> |
| ^ | | Bitwise exclusive `OR' and regular `OR' |
| <= < > >= | Comparison operators |
| <> == != | Equality operators |
| = %= /= //= -= += *= **= | Assignment operators |
| is is not | Identity operators |
| in not in | Membership operators |
| not or and | Logical operators |
Operator precedence affects how an expression is evaluated.
For example, x = 7 + 3 * 2; here, x is assigned 13, not 20 because operator * has higher precedence than +, so it first multiplies 3*2 and then adds into 7.
Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom.
Example
#!/usr/bin/python3 a = 20 b = 10 c = 15 d = 5 print ("a:%d b:%d c:%d d:%d" % (a,b,c,d )) e = (a + b) * c / d #( 30 * 15 ) / 5 print ("Value of (a + b) * c / d is ", e) e = ((a + b) * c) / d # (30 * 15 ) / 5 print ("Value of ((a + b) * c) / d is ", e) e = (a + b) * (c / d) # (30) * (15/5) print ("Value of (a + b) * (c / d) is ", e) e = a + (b * c) / d # 20 + (150/5) print ("Value of a + (b * c) / d is ", e)
When you execute the above program, it produces the following result −
a:20 b:10 c:15 d:5 Value of (a + b) * c / d is 90.0 Value of ((a + b) * c) / d is 90.0 Value of (a + b) * (c / d) is 90.0 Value of a + (b * c) / d is 50.0
