Python Tutorial : Loop

Python Tutorial : Loop

                    Python is one of the popular language programming language , Python are very popular since 1980 for its simplicity , easy of learning and code under stability for both beginner and professional level . Python code are smart , need less code compared to other programming language and syntax are easy to understand.  Lot of Inbuild library are integrated with Python for different work  , other than that many third party libraries specially for Artificial Intelligence model training third party libraries are very popular .

                 In this article we will learn about "loop" ,  what is loop ? loop is nothing but approach for examination of every object , for example a string "This is a python code" , if i need every character of this string , I need to use "loop",  "loop" will return every character unless there is any stopping condition . Python support two kind of loop , "for loop" and "While" loop , both are very popular in this days.

for loop — iterates over a sequence (like list, tuple, dictionary, string)

while loop — runs as long as a condition is True 

Example of for loop

Example 1
fruits = ["apple", "banana", "mango"]
for fruit in fruits:
    print(fruit)

output
apple
banana
mango

Example 2
for letter in "Python":
    print(letter)

output

P
y
t
h
o
n

Example of while loop

Example 1

count = 1
while count <= 5:
    print("Count:", count)
    count += 1

output

Count: 1

Count: 2

Count: 3

Count: 4

Count: 5

Some More Topic about Loop:

1. break
2. continue
3. pass
4. else with loops
5. Nested loops

1.break : Break statement break loop for a particular conditions .Loop stops  iterating when it reach to break statement.

Example 1

for i in range(10):
    if i == 5:
        break
    print(i)

output

0 1 2 3 4

2.continue  :continue statement skips the current iteration , that means if any condition satisfy ,loop will bypass the condition.  

Example 1

for i in range(10):

    if i % 2 == 0:

        continue

    print(i)

output

1 3 5 7 9

3.pass : pass do nothing , simple tell the program to do the next work 

Example 1

for i in range(5):

    pass

print("Loop finished!")

output

Loop finished!

4.else with loops : We can write if else condition withing the loop , if condition satisfied do one thing else do another thing.

Example 1

word = "Python"

for ch in word:

    if ch.lower() in ['a', 'e', 'i', 'o', 'u']:

        print(ch, "is a vowel")

    else:

        print(ch, "is a consonant")

output

P is a consonant
y is a consonant
t is a consonant
h is a consonant
o is a vowel
n is a consonant

5.Nested loops :  A loop can be under another loop , may be for loop under for loop or for loop under while loop etc.

Example 1

for i in range(1, 6):      
    for j in range(1, 6):   
        print(i * j, end="\t")
        print() 

output

1 2 3 4 5

2 4 6 8 10

3 6 9 12 15

4 8 12 16 20

5 10 15 20 25

Example 2

i = 1
while i <= 3:
    j = 1
    while j <= 3:
        print(f"i={i}, j={j}")
        j += 1
    i += 1

output

i=1, j=1
i=1, j=2
i=1, j=3
i=2, j=1
i=2, j=2
i=2, j=3
i=3, j=1
i=3, j=2
i=3, j=3

Some Unique Fact of Python Loop

Backward Looping :Pyhon loop can be reverse direction also using reversed()

for i in reversed(range(1, 6)):

    print(i)

Add an else Clause to a Loop :Very Unique feature which is not available in other programming language 

 for i in range(5):
    print(i)
else:
    print("Loop finished without break!")

Looping Over Multiple Sequences Together 

names = ["Ayan", "Riya", "Rohan"]
scores = [85, 92, 78]

for n, s in zip(names, scores):
    print(n, "scored", s)
 

output

Ayan scored 85
Riya scored 92
Rohan scored 78