(3)_flow-control.py

# Python Flow Control
# ========================
# Adapted From: Programiz
# Tutorial Title: Python Flow Control
# URL: https://www.programiz.com/python-programming

# 1. Python if ... else
# ----------------------
# In Python, there are three forms of the 'if ... else' statement:
# i. if statement
# Example 1: Python if Statement
number = 10
# check if number is greater than 0
if number > 0:
    print('Number is positive.')
print('The if statement is easy')

# ii. if ... else statement
# Example 2. Python if...else Statement
number = 10
# check if number is greater than 0
if number > 0:
    print('Positive number')
else:
    print('Negative number')
print('This statement is always executed')

# iii.if ... elif ... else statement
# Example 3: Python if...elif...else Statement
number = 0
if number > 0:
    print("Positive number")
elif number == 0:
    print('Zero')
else:
    print('Negative number')
print('This statement is always executed')

# 2. Python Nested if statements
# -------------------------------
# Example 4: Python Nested if Statement
number = 5
# outer if statement
if (number >= 0):
    # inner if statement
    if number == 0:
        print('Number is 0')
    # inner else statement
    else:
        print('Number is positive')
# outer else statement
else:
    print('Number is negative')
# Output: Number is positive


# 3. Python for Loop
# -------------------
# Definition: In Python, the for loop is used to run a block of code for a certain number of times.
# It is used to iterate over any sequences such as lists, tuples, string, etc.
# Example: Loop Over Python List
programming_languages = ['Swift', 'Python', 'Go', 'JavaScript']
for language in programming_languages:
    print(language)

# Python for Loop with Python range()
# A 'range' is a series of values between two numeric intervals.
# We use Python's built-in function range() to define a range of values. For example,
# use of range() to define a range of values
values = range(4)
# iterate from i = 0 to i = 3
for i in values:
    print(i)

# Python for loop with else
# Definition: A 'for' loop can have an optional else block as well. The 'else' part is executed when the loop is finished. For example,
digits = [0, 1, 5]
for i in digits:
    print(i)
else:
    print("No items left.")


# 4. Python while Loop
# ----------------------
# Definition: Python while loop is used to run a specified code until a certain condition is met.
# Example 1: Python while Loop
i = 1
n = 5
while i <= n:
    print(i)
    i = i + 1

# Example 2: Python while Loop to Display Game Level
current_level = 0
final_level = 5
game_completed = True
while current_level <= final_level:
    if game_completed:
        print('You have passed level', current_level)
        current_level += 1
print('Level Ends')

# Infinite while Loop in Python
# If the condition of a loop is always True, the loop runs for infinite times (until the memory is full). For example,
# infinite while loop
# while True:
    # body of the loop
# In the above example, the condition is always True. Hence, the loop body will run for infinite times.

# Python While loop with else
# A while loop can have an optional else block as well.
# The else part is executed after the condition in the while loop evaluates to False. For example,
counter = 0
while counter < 3:
    print('Inside loop')
    counter = counter + 1
else:
    print('Inside else')

# Python for vs while loops
# The for loop is usually used when the number of iterations is known. For example,
# this loop is iterated 4 times (0 to 3)
for i in range(4):
    print(i)

# And while loop is usually used when the number of iterations are unknown. For example,
# while condition:
    # body of loop

# 5. Python break and continue
# -----------------------------
# The break statement is used to terminate the loop immediately when it is encountered.
# Syntax: break
# Example 1: Python break Statement with for Loop
for i in range(5):
    if i == 3:
        break
    print(i)

# Example 2: Python break Statement with while Loop
# program to find first 5 multiples of 6
i = 1
while (i <= 10):
    print('6 * ', (i), '=', 6 * i)
    if i >= 5:
        break
    i = i + 1

# The continue statement is used to skip the current iteration of the loop and the control flow of the program goes to the next iteration.
# Syntax: continue
# Example 1: Python continue Statement with for Loop
for i in range(5):
    if i == 3:
        continue
    print(i)

# Example 2: Python continue Statement with while Loop
# program to print odd numbers from 1 to 10
num = 0
while num < 10:
    num += 1
    if (num % 2) == 0:
        continue
    print(num)

# 6. Python Pass
# ---------------
# Definition: In Python programming, the pass statement is a null statement which can be used as a placeholder for future code.
# Suppose we have a loop or a function that is not implemented yet, but we want to implement it in the future. In such cases, we can use the pass statement.
# Syntax: pass
# Example 1: Using pass With Conditional Statement
n = 10
# use pass inside if statement
if n > 10:
    pass
print('Hello')