Python Tutorials
- Python
- How to install Python?
- PIP
- How to Run Python Program
- Python Identifiers,Statement, Indentation and Comments
- Variable
- Data type
- Decision Making
- Python Loops
- Break,Continue, Pass
- Functions
- Predefine Functions
- Lambda Functions
- Variable Scope
- List
- Tuple
- Python Sets
- Python Dictionary
- Python String
- String Formating
- Input/Output
- File Handling (Input / Output)
- Iterators
- Python Modules
- Python Date
- Python JSON
- Classes and Objects
- Constructor
- Polymorphism
- Encapsulation
- inheritance
- Class or Static Variables in Python
- class method vs static method
- Abstraction
- Exception Handling
- MySql Python
- MySql Create Database
- MySql CRUD
- Django
What is Loop in Python?
A loop statement allows us to execute a statement or group of statements multiple times.
Loops are used to repeat a specific block of code.
File name : index.py
While loop
do-while loop
for loop
nested loop
while loop
The while loop in Python is used to iterate over a block of code as long as the test expression (condition) is true.
We generally use this loop when we don't know the number of iterations then the while loop is most effective to use.
File name : index.py
while expression:
statements
Example
File name : index.py
n = 10
# initialize sum and counter
sum = 0
i = 1
while i <= n:
sum = sum + i
i = i+1 # update counter
# print the sum
print("The sum is", sum)
Example
File name : index.py
# prints all letters except 'a' and 't'
i = 0
str1 = 'javatpoint'
while i < len(str1):
if str1[i] == 'a' or str1[i] == 't':
i += 1
continue
print('Current Letter :', a[i])
i += 1
File name : index.py
# The control transfer is transfered
# when break statement soon it sees t
i = 0
str1 = 'javatpoint'
while i < len(str1):
if str1[i] == 't':
i += 1
break
print('Current Letter :', str1[i])
i += 1
print 1 to 10 using while loop
File name : index.py
i=1
#The while loop will iterate until condition becomes false.
While(i<=10):
print(i)
i=i+1
Program to print table of given numbers
File name : index.py
i=1
number=0
b=9
number = int(input("Enter the number:"))
while i<=10:
print("%d X %d = %d \n"%(number,i,number*i))
i = i+1
Using else with while loop
Python allows us to use the else statement with the while loop also. The else block is executed when the condition given in the while statement becomes false. Like for loop, if the while loop is broken using break statement, then the else block will not be executed, and the statement present after else block will be executed. The else statement is optional to use with the while loop.
File name : index.py
i=1
while(i<=5):
print(i)
i=i+1
else:
print("The while loop exhausted")
For Loop
A for loop is used for iterating over a sequence (that is either a list, a tuple, a dictionary, a set, or a string).
File name : index.py
str = "Python"
for i in str:
print(i)
Output :-
P
y
t
h
o
n
for loop
File name : index.py
# Program to find the sum of all numbers stored in a list
# List of numbers
numbers = [6, 5, 3, 8, 4, 2, 5, 4, 11]
# variable to store the sum
sum = 0
# iterate over the list
for val in numbers:
sum = sum+val
print("The sum is", sum)
Example
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list = [1,2,3,4,5,6,7,8,9,10]
n = 5
for i in list:
c = n*i
print(c)
Output :-
10
15
20
25
30
35
40
45
50
Nested for loop in python
Python allows us to nest any number of for loops inside a for loop. The inner loop is executed n number of times for every iteration of the outer loop.
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for iterating_var1 in sequence: #outer loop
for iterating_var2 in sequence: #inner loop
#block of statements
#Other statements
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# User input for number of rows
rows = int(input("Enter the rows:"))
# Outer loop will print number of rows
for i in range(0,rows+1):
# Inner loop will print number of Astrisk
for j in range(i):
print("*",end = '')
print()
File name : index.py
File name : index.py
File name : index.py
File name : index.py