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The Usefulness of For and While Loop in Python

One of the essential building blocks in programming is the loop. The main function of a loop is to verify whether a certain condition in a piece of code is true; if it is, the loop executes to produce the desired output. Unless the situation changes, this code will continue to run.

Developers use loops to repeatedly execute a piece of code until a particular condition is met. Thus, it speeds up development and improves code readability.

This article will use different examples to explain the for and while loop in Python.

Understanding the For and While Loop in Python 

Python is one of the most user-friendly programming languages you can use to build websites and software and conduct analysis. In Python, there are two different types of loop structures: FOR and WHILE loops.

You can use both to execute the same condition, but the “for” loop structure only requires initialization to occur once rather than repeatedly. You can iterate over a condition “n” times with a FOR loop. And you can use it to iterate over a list or a string. On the other hand, until the condition is false, a WHILE loop iterates continuously. The ”while” loop iterates until a condition is satisfied. 

Let’s look at some Python examples of for and while loop implementations.

For and While Loops in Python: How They Work

You can use the for and while loops to repeat tasks in a more efficient manner. 

How to use a for loop in Python

Example one: Using a for loop to iterate over a list

fruits = ["strawberry ", "pear", "cherry", "orange"]
for x in fruits:
  print(x) 

#output

strawberry 

pear

cherry

orange

Introducing a break statement to the loop

fruits = ["strawberry ", "pear", "cherry", "orange", "carrot", "cashew", "mango"]
# break halts the program once it meets the x value
for x in fruits:
  if x == "mango":
    break
  print(x)

#output

strawberry 

pear

cherry

orange

carrot

cashew

Example 2: Using a for loop to iterate over a range of numbers

#Define for loop
#Using range here x will start from values after 1 and before 10
x=0
for x in range(1,10):
     print(x)

#output

1

2

3

4

5

5

6

7

8

9

Example 3: Using a for loop for strings

for x in "documentation ":
  print(x)
else:
  print(" nothing else to execute!")

#output

d

o

c

u

m

e

n

t

a

t

i

o

n

nothing else to execute!

How to use a while loop in Python

Example 1: Using a while loop to print even numbers

y=0
#while loop example
while(y < 20):
    print(x)
    x = x+2

#output

2

4

6

8

10

12

14

16

18

Example 2: Using a while loop with a list

 a = ['daze', 'cost', 'food', 'goat']
 while a:
    print(a.pop(-1))

#output

goat

food

cost

daze

Example 3: Using else Statement with While Loop

nitro = 0
while nitro < 3:
   print nitro, " is  less than 3"
   nitro = nitro + 1
else:
   print("oops's!!!!!!")
   print nitro, " is not less than 3"

#output

0 is less than 3

1 is less than 3

2 is less than 3

oops’s!!!!!!

3 is not less than 3

How to Use Break Statements With a For Loop

If you want to exit a loop or skip part of a loop, you can achieve this with a break statement.

You can use a break statement to break or terminate an ongoing program when it encounters a certain condition. 

for x in range(10,20):
   if (x == 15):
      break
   print(x)

#output

10

11

12

13

14

Using a break statement with a list

Friends_list=["mika","Hassan","khan","Maria","Ralph","Sean"]
for n in Friends_list:
    if n == "Ralph":
            # break here
        print('This operation ended because we came across a break command when we met with Mr.',n)
        break
    print(n)

#output

Mika

Hassan

khan

Maria

This operation ended because we came across a break command when we met with Mr. Ralph.

Note: The break statement will not allow a loop to satisfy the original condition if it meets a condition that triggers it. It brings the operation to an abrupt end.

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