3. Operators
3.1 Arithmetic operators
- Arithmetic operator is a type of operator
- It is a symbol used to complete basic arithmetic operations and is used to process four arithmetic operations
| operator |
describe |
example |
| + |
add |
10 + 20 = 30 |
| - |
reduce |
10 - 20 = -10 |
| * |
take |
10 * 20 = 200 |
| / |
remove |
10 / 20 = 0.5 |
| // |
Divide |
Returns the integer part (quotient) of the division 9 // 2 outputs the result 4 |
| % |
take the remainder |
Returns the remainder of division 9 % 2 = 1 |
| ** |
power |
Also known as power, power, 2 ** 3 = 8 |
- In Python, the * operator can also be used for strings, and the result of the calculation is the result of repeating the string a specified number of times
In [1]: "-" * 50
Out[1]: '----------------------------------------'
Arithmetic operator precedence
- First multiply and divide and then add and subtract . The same level operators are calculated from left to right. You can use () to adjust the priority of the calculation
| operator |
describe |
priority |
| ** |
power (highest priority) |
high |
| * / % // |
Multiply, Divide, Remainder, Divide |
middle |
| + - |
addition, subtraction |
Low |
3.2 Comparison (relational) operators
| operator |
describe |
| == |
Checks whether the values of the two operands are equal , if so, the condition is true and returns True |
| != |
Checks if the values of the two operands are not equal , if so, the condition is true and returns True |
| > |
Check if the value of the left operand is greater than the right operand, if so, the condition is true, return True |
| < |
Check if the value of the left operand is less than the right operand, if so, the condition is true and return True |
| >= |
Check if the value of the left operand is greater than or equal to the value of the right operand, if so, the condition is true, return True |
| <= |
Check if the value of the left operand is less than or equal to the value of the right operand, if so, the condition is true, return True |
In Python 2.x , you can also use the <> operator to judge not equal to
!= can also be used to judge not
3.3 Logical Operators
| operator |
logical expression |
describe |
| and |
x and y |
Returns True only if both x and y are True, otherwise returns False as long as either x or y has a value of False |
| or |
x or y |
Returns True as long as either x or y has a value of True, and returns False only if both x and y are False |
| not |
not x |
Returns False if x is True and returns True if x is False |
3.4 Assignment operator
- In Python, use = to assign values to variables
- In arithmetic operations, in order to simplify the writing of code, Python also provides a series of assignment operators corresponding to arithmetic operators
- Note: Spaces cannot be used between assignment operators
| operator |
describe |
example |
| = |
simple assignment operator |
c = a + b assigns the result of the operation of a + b to c |
| += |
addition assignment operator |
c += a is equivalent to c = c + a |
| -= |
Subtraction assignment operator |
c -= a is equivalent to c = c - a |
| *= |
multiplication assignment operator |
c *= a is equivalent to c = c * a |
| /= |
division assignment operator |
c /= a is equivalent to c = c / a |
| //= |
Integer division assignment operator |
c //= a is equivalent to c = c // a |
| %= |
modulo (remainder) assignment operator |
c %= a is equivalent to c = c % a |
| **= |
exponentiation assignment operator |
c = a is equivalent to c = c a |
3.5 Precedence of operators
- Arithmetic precedence in the following table is in order from highest to lowest
| operator |
describe |
| ** |
power (highest priority) |
| * / % // |
Multiply, Divide, Remainder, Divide |
| + - |
addition, subtraction |
| <= < > >= |
comparison operator |
| == != |
equals operator |
| = %= /= //= -= += *= **= |
assignment operator |
| not or and |
Logical Operators |