A Short notes on Python Programming
Arithmetic Operators
|
Operator |
Operation |
Expression |
English description |
Result |
|
|
addition |
|
11 plus 56 |
67 |
|
|
subtraction |
|
23 minus 52 |
-29 |
|
|
multiplication |
|
4 multiplied by 5 |
20 |
|
|
exponentiation |
|
2 to the power of 5 |
32 |
|
|
division |
|
9 divided by 2 |
4.5 |
|
|
integer division |
|
9 divided by 2 |
4 |
|
|
modulo (remainder) |
|
9 mod 2 |
1 |
Types int and float
A type is a set of values and operations that can be performed on those values.
Two of Python's numeric types:
·
int: integer
For example: 3, 4, 894, 0, -3, -18
·
float: floating point number (an approximation
to a real number)
For example: 5.6, 7.342, 53452.0, 0.0, -89.34, -9.5
Arithmetic Operator Precedence
When multiple operators are combined in a single expression, the operations are evaluated in order of precedence.
|
Operator |
Precedence |
|
** |
highest |
|
- (negation) |
|
|
*, /, /, % |
|
|
+ (addition), - (subtraction) |
lowest |
Syntax and Semantics
Syntax: the rules that describe valid combinations of Python symbols
Semantics: the meaning of a combination of Python symbols is the meaning of an instruction — what a particular combination of symbols does when you execute it.
Errors
A syntax error occurs when we an instruction with invalid syntax is executed. For example:
>>> 3) + 2 * 4
SyntaxError: invalid syntax
A semantic error occurs when an instruction with invalid semantics is executed. For example:
>>> 89.4 / 0
Traceback (most recent call last):
File "", line 1, in
89.4 / 0
ZeroDivisionError: float division by zero