Statements in python
There are two major types of statements in python : simple and compound statements
Simple statement in python
As the name suggests, simple statement are comprised in a one single line.
These types of statements will never affect flow of program.
There are many simple statements like assert, break, continue, pass ,del,import, return, etc
Expression Statement
This type of statements are formed using operators, variables or values which create one mathematical expression.
Example:
>>> i=5
>>> v=i-2
>>> v
3
>>> z=i**2
>>> z
25
>>>
Assignment Statement
In this type of statement we assign value to a variable.
This statement has one equal (=) sign.
We cannot set keyword as a variable name.
Example:
>>> i=5
>>> a=10
>>> #keyword cannot be used in asignment
>>> for=5
SyntaxError: invalid syntax
>>> z='itvoyagers'
assert Statement
This statements are use to check condition if the condition returns ‘true’ then it will simply go on next line but if the condition statements returns false then it will stop the program execution and displays the error.
Example:
x = [1,2,3,4]
#if condition returns True, then nothing happens:
assert x == [1,2,3,4]
#if condition returns False, AssertionError is raised:
assert x == [1,2,3,4,5]
Output :
Traceback (most recent call last):
File "C:Python34sep11.py", line 7, in <module>
assert x == [1,2,3,4,5]
AssertionError
del Statement
It is used to delete a name or variable.
>>> p=80
>>> q=p
>>> del p
>>> p
Traceback (most recent call last):
File "<pyshell#16>", line 1, in
p
NameError: name 'p' is not defined
>>> q
80
>>> z=80
>>> id(q) #checks location of 80
1385289408
>>> id(z) #checks location of 80
1385289408
>>>
EXPLANATION : This proves that here del statement deletes on variable name and not the value. If we assign same value to another variable it creates new reference to the value present in same location.
Augmented Statement
In augmented statement all arithmetic operators like +,-,*,/,//,%,** are suffixed with equal to symbol (=).
This operators states which operation is to be perform on both the values and it stores the result value in variable which is on left side of expression.
In augmented statement each step preserves the output and next step uses previous output for next operation.
This means continuously updated values are fed to next step for further execution.
Example :
>>> m=10
>>> m
10
>>> m+=5
>>> m
15
>>> m-=2
>>> m
13
>>> m*=2
>>> m
26
>>> m/=2
>>> m
13.0
>>>
import Statement
As the name says, “import” statement allows us to add another file (module) completely or to add part (class or method) from a file in our program.
Example :
>>>import math # it will include entire time module in our program with its methods and classes >>>math.sqrt(25)
5
>>> math.pi
3.141592653589793
Compound Statement in Python
These statements may affect flow of execution.
There are many compound statements like if, for, while, try, with, class etc.
if Statement
In this, if statement will check for certain condition and if the condition is true then it will execute block of code written in it.
Example :
if 0:
print ("if condition is true i will be printed")
print("if condition is false i will be printed") Output :
if condition is false i will be printed
for Statement
In python for loop is used to iterate over a sequence like list,string, tuple etc and other iterable objects.
Example :
print("Output of for loop using range()")
for m in list(range(10)):
print(m) Output :
Output of for loop using range()
0
1
2
3
4
5
6
7
8
9
while Statement
In python while loop is used to iterate over a sequence like list,string, tuple etc and other iterable objects.
Example :
counter=0
while counter < 10:
print("count is",counter)
counter+=1 Output :
count is 0
count is 1
count is 2
count is 3
count is 4
count is 5
count is 6
count is 7
count is 8
count is 9
try Statement
In python try statement is used to handle exceptions.
Example :
try:
val=int(input("enter a number"))
print("value accepted")
except ValueError:
print("integer number expected") Output :
>>> enter a number5 value accepted >>> ================================ RESTART ================================ >>> enter a number0 value accepted >>> ================================ RESTART ================================ >>> enter a number2.3 integer number expected >>>
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