Today, we're continuing our 10-day journey to learn Python, kicking off Day 3's lesson. If you haven't checked out Day 1 yet, you can find it here: ðLearn Python in 10 Days: Day 1
Hey there! Let's dive into loops in Python, using some everyday examples and some hands-on coding. Here's a breakdown of the main points, all formatted nicely for you.
Day 3: Loop Statements ð
Loops are everywhere in our daily lives, and just like that, they play a crucial role in programming as well. Let's get down to the basics of loops in Python! ðâĻ
1. Basic Syntax of the while
Loop
Basic while
Loop in Python:
i = 0
while i < 100:
print("Hello, world!")
i += 1
-
Explanation:
- The
while
loop continues as long as the condition isTrue
. - You need to set a condition to stop the loop, like
i += 1
paired withi < 100
to avoid an infinite loop. - Indentation is crucial, just like with
if
statements.
- The
Example: Sum of Numbers from 1 to 100
i = 1
total = 0
while i <= 100:
total += i
i += 1
print(f"The total sum is: {total}")
Example: Guess the Number Game
import random
num = random.randint(1, 100)
count = 0
flag = True
while flag:
guess_num = int(input("Guess the number: "))
count += 1
if guess_num == num:
print("Congratulations! You guessed it!")
flag = False
elif guess_num > num:
print("Too high!")
else:
print("Too low!")
print(f"You guessed it in {count} tries.")
2. Nested while
Loops
Example: Sum of Factorials from 1 to 100
i = 1
total_sum = 0
while i <= 100:
fact = 1
j = 1
while j <= i:
fact *= j
j += 1
total_sum += fact
i += 1
print(total_sum)
Example: Multiplication Table (9x9)
i = 1
while i <= 9:
j = 1
while j <= i:
print(f"{i}*{j}={i*j}\t", end='')
j += 1
i += 1
print() # New line after each row
3. Basic Syntax of the for
Loop
- Unlike
while
,for
loops are used for iterating over a sequence (like a list, tuple, dictionary, set, or string).
Example: Iterating Over a String
name = "Bob"
for char in name:
print(char, end='')
Example: Counting Occurrences of 'a' in a String
sample_str = "abcdefaac"
count = 0
for char in sample_str:
if char == 'a':
count += 1
print(count)
range()
Function:
-
Syntax 1:
range(num)
generates numbers from 0 to num-1. -
Syntax 2:
range(start, end)
generates numbers from start to end-1. -
Syntax 3:
range(start, end, step)
uses a step value.
Example: Counting Even Numbers
num = int(input("Enter a number: "))
count = 0
for x in range(1, num):
if x % 2 == 0:
count += 1
print(count)
4. Nested for
Loops
Example: Multiplication Table (9x9) with for
Loops
for i in range(1, 10):
for j in range(1, i+1):
print(f"{i}*{j}={i*j}\t", end='')
print() # New line after each row
5. Loop Control Statements: break
and continue
-
continue
: Skips the rest of the code inside the loop for the current iteration only. -
break
: Terminates the loop.
Example: Payroll with Performance Check
money = 10000
for num in range(1, 21):
grade = random.randint(1, 10)
if grade < 5:
print(f"Employee {num} has a performance score below 5. No salary issued.")
continue
if money >= 1000:
money -= 1000
print(f"Employee {num} meets performance criteria. Company balance: {money}")
else:
print(f"Insufficient funds. Balance: {money}")
break
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