“if…else” statement in Python part3

The “if…else” statement is a fundamental control structure in Python that allows programmers to execute certain code based on whether a particular condition is true or false. This statement is commonly used in programming to control the flow of execution, and it is essential for making decisions in the code. In Python, the “if…else” statement is used to test a condition and execute a set of statements if the condition is true, and another set of statements if the condition is false. This article provides an overview of how to use the “if…else” statement in Python, as well as some examples of its usage.

here are some more examples and uses of the “if…else” statement in Python:

Example 42: If…Else with Ternary Operator

x = 10

result = “x is greater than 5” if x > 5 else “x is less than or equal to 5”

print(result)

Output: x is greater than 5

Explanation: In this example, we use the ternary operator in conjunction with the “if…else” statement to assign a value to a variable “result” based on the value of a variable “x”. We assign the value 10 to “x”. We use the ternary operator to check if “x” is greater than 5. If it is, we assign the string “x is greater than 5” to the variable “result”. If it is not, we assign the string “x is less than or equal to 5” to the variable “result”. Since “x” is greater than 5, the output will be “x is greater than 5”.

Example 43: If…Else with Boolean Operators

x = 5
y = 10

if x > 0 and y > 0:
    print("Both x and y are positive")
elif x > 0 or y > 0:
    print("At least one of x and y is positive")
else:
    print("Both x and y are non-positive")

Output: At least one of x and y is positive

Explanation: In this example, we use the “if…else” statement with boolean operators to check the values of two variables “x” and “y”. We assign the values 5 and 10 to “x” and “y”, respectively. We use the “and” operator to check if both “x” and “y” are positive. If they are, we print a message that says “Both x and y are positive”. If they are not, we move on to the “elif” block and use the “or” operator to check if at least one of “x” and “y” is positive. If it is, we print a message that says “At least one of x and y is positive”. If neither of the conditions is true, we move on to the “else” block and print a message that says “Both x and y are non-positive”. Since “x” is positive, but “y” is not, the output will be “At least one of x and y is positive”.

Example 44: If…Else with Nested Statements

x = 5

if x > 0:
    if x > 10:
        print("x is greater than 10")
    else:
        print("x is between 0 and 10")
else:
    print("x is non-positive")

Elif and its uses with examples 

The elif statement in Python is short for “else if”. It is used to specify a new condition to test if the previous condition(s) in an if statement evaluate to False. Here are some examples of how to use elif in Python:

Example 45: Using Elif with Multiple Conditions

 

x = 10

if x > 15:
    print("x is greater than 15")
elif x > 10:
    print("x is greater than 10")
elif x > 5:
    print("x is greater than 5")
else:
    print("x is less than or equal to 5")
 

Output: x is greater than 10

Explanation: In this example, we use the elif statement to specify multiple conditions to test if the previous conditions in the if statement evaluate to False. We assign the value 10 to x. The first condition checks if x is greater than 15, which is False. The second condition checks if x is greater than 10, which is True. Therefore, the code inside the second if block is executed and the output is “x is greater than 10”.

Example 46: Using Elif to Simplify Code

x = 10

if x == 1:
    print("x is 1")
elif x == 2:
    print("x is 2")
elif x == 3:
    print("x is 3")
elif x == 4:
    print("x is 4")
elif x == 5:
    print("x is 5")
else:
    print("x is not between 1 and 5")

Output: x is not between 1 and 5

Explanation: In this example, we use the elif statement to simplify the code that checks if x is equal to any of the numbers from 1 to 5. If we used if statements instead, we would have to test each condition separately, which would result in longer code. Since x is not equal to any of the numbers from 1 to 5, the output is “x is not between 1 and 5”.

Example 47: Using Elif with Nested Statements

x = 10

if x > 0:
    if x < 20:
        print("x is between 0 and 20")
    elif x < 30:
        print("x is between 20 and 30")
    else:
        print("x is greater than or equal to 30")
else:
    print("x is less than or equal to 0")

Output: x is between 0 and 20

Explanation: In this example, we use the elif statement with nested statements to check if x is between 0 and 20, between 20 and 30, or greater than or equal to 30. The outer if statement checks if x is greater than 0. If it is, the inner if statement checks if x is less than 20. If it is, the code inside the first if block is executed and the output is “x is between 0 and 20”. If it is not, the first elif statement checks if x is less than 30. If it is, the code inside the second if block is executed and the output is “x is between 20 and 30”. If neither of the conditions is True, the else block is executed and the output is “x is greater than or equal to 30”.

Short Hand If and its uses with example

In Python, a short-hand if statement is a condensed way to write an if statement when you only need to execute a single statement based on a condition. It has the following syntax:

result = value_if_true if condition else value_if_false


This statement checks a condition, and if it’s true, it returns the value value_if_true. Otherwise, it returns value_if_false. Here are some examples of how to use the short-hand if statement in Python:

Example 48: Using Short-Hand If

x = 10

y = "greater than 5" if x > 5 else "less than or equal to 5"

print(y)


Output: greater than 5

Explanation: In this example, we use the short-hand if statement to assign a value to y based on the condition x > 5. Since x is greater than 5, the value "greater than 5" is assigned to y.

Example 49: Using Short-Hand If in a Function

def is_even(number):
    return "even" if number % 2 == 0 else "odd"

print(is_even(4))
print(is_even(7))
 Output:
even
odd

Explanation: In this example, we use the short-hand if statement inside a function to return the string "even" if the input number is even, and "odd" otherwise.

Example 50: Using Short-Hand If to Check for Empty Lists

my_list = [1, 2, 3]
result = "list is not empty" if my_list else "list is empty"
print(result)
my_list = []
result = "list is not empty" if my_list else "list is empty"
print(result)

Short Hand If … Else its uses

In Python, you can also use the short-hand if...else statement to execute two different statements based on a condition in a single line of code. It has the following syntax:

value_if_true if condition else value_if_false


This statement checks a condition, and if it’s true, it returns the value value_if_true. Otherwise, it returns value_if_false. Here are some examples of how to use the short-hand if...else statement in Python:

Example 51: Using Short-Hand If…Else

x = 10

print("x is greater than 5" if x > 5 else "x is less than or equal to 5")


Output: x is greater than 5

Explanation: In this example, we use the short-hand if...else statement to print a message based on the condition x > 5. Since x is greater than 5, the message "x is greater than 5" is printed.

Example 52: Using Short-Hand If…Else in a Function

def is_even(number):
    return "even" if number % 2 == 0 else "odd"
print(is_even(4))
print(is_even(7))
 
Output:
even
odd

Explanation: In this example, we use the short-hand if...else statement inside a function to return the string "even" if the input number is even, and "odd" otherwise.

Example 53: Using Short-Hand If…Else with Mathematical Operations

x = 5

y = 10

result = x * y if x > y else x + y

print(result)


Output: 15

Explanation: In this example, we use the short-hand if...else statement to calculate the value of result based on the condition x > y. Since x is not greater than y, the value of x + y is assigned to result.

The short-hand if...else statement is useful when you need to perform a simple conditional operation in a single line of code. However, it can become harder to read and understand if you have multiple conditions or statements to execute based on a condition, in which case you should use a regular if...else statement.

Nested If

In Python, a nested if statement is used when we have an if statement inside another if statement. This means that the second if statement is executed only if the first if statement is true. Here is the syntax for a nested if statement:

if condition1:
    # execute this block of code if condition1 is true
    if condition2:
        # execute this block of code if both condition1 and condition2 are true

The inner if statement is indented to show that it is inside the outer if statement. Here is an example of how to use nested if statements in Python:

Example 54: Using Nested If Statements

x = 10
y = 20

if x > 5:
    print("x is greater than 5")
    if y > 15:
        print("y is greater than 15")
    else:
        print("y is less than or equal to 15")
else:
    print("x is less than or equal to 5")
 

Output:

x is greater than 5
y is greater than 15

Explanation: In this example, we use nested if statements to check whether x is greater than 5, and whether y is greater than 15. Since both conditions are true, the message "x is greater than 5" and "y is greater than 15" are printed.

Nested if statements can be used to check for more complex conditions, or to check for multiple conditions before executing a block of code. However, it is important to ensure that your code remains readable and maintainable, and that you do not nest too many if statements, as this can make your code harder to understand.

The pass Statement

In Python, the pass statement is used as a placeholder for empty blocks of code. It is used when a statement is required syntactically, but you don’t want to execute any code. It can also be used as a placeholder when writing code that is not complete.

Here is the syntax for the pass statement:

if condition:
    pass

The pass statement simply does nothing and allows the code to continue running without any errors. It is often used in situations where you want to indicate that a block of code will be implemented later.

Example 55: Using the Pass Statement

x = 10

if x > 5:
    pass
else:
    print("x is less than or equal to 5")
 

Output:

(No output is generated because the condition x > 5 is true and the pass statement does nothing)

Explanation: In this example, we use the pass statement to create an empty block of code. If x is greater than 5, the pass statement is executed and nothing happens. If x is less than or equal to 5, the else block is executed and the message "x is less than or equal to 5" is printed.

The pass statement is also commonly used in the definition of functions, classes, and loops where a code block is expected. It can be used to temporarily define a function or class without implementing any functionality or to create an empty loop.

Quiz multichoice quiz

1. What is the output of the following code?

 

x = 10
if x > 5:
    print("x is greater than 5")
else:
    print("x is less than or equal to 5")

a) “x is greater than 5” b) “x is less than or equal to 5” c) Both a and b d) None of the above

2. Which of the following statements is true about the elif statement?

a) It can only be used once in a Python program b) It is used to test another condition if the previous if statement evaluated to false c) It is used to end a loop prematurely d) None of the above

3. What is the output of the following code?

x = 5
y = 10
z = x if x > y else y
print(z)

a) 5 b) 10 c) “x is greater than y” d) None of the above

4. What is a nested if statement?

a) An if statement that is inside a loop b) An if statement that is inside another if statement c) An if statement that is used to test for multiple conditions d) None of the above

5. What is the purpose of the pass statement in Python?

a) To exit a loop prematurely b) To test a condition c) To add a placeholder for empty code blocks d) None of the above

Answers:

1. a) “x is greater than 5”
2. b) It is used to test another condition if the previous if statement evaluated to false
3. b) 10
4. b) An if statement that is inside another if statement
5. c) To add a placeholder for empty code blocks

quiz2

1. Which keyword is used to begin an if statement in Python? a) for b) while c) if d) switch

2. What is the syntax for an if-else statement in Python? a)

if condition:
    # code to execute if condition is true
else:
    # code to execute if condition is false
 b)
if condition:
    # code to execute if condition is true
elif condition2:
    # code to execute if condition2 is true
else:
    # code to execute if both condition and condition2 are false

c)
if condition:
    # code to execute if condition is true
    else:
    # code to execute if condition is false
d)
if condition:
    # code to execute if condition is true
    elif condition2:
    # code to execute if condition2 is true
    else:
    # code to execute if both condition and condition2 are false

3. What is the purpose of a break statement in a loop?

a) To end the current iteration of the loop and move on to the next iteration

b) To exit the loop completely

c) To skip over a certain number of iterations in the loop

d) None of the above

3)What is the syntax for a shorthand if statement in Python?

a) condition ? value_if_true : value_if_false

b) condition if value_if_true else value_if_false

c) if condition: value_if_true else: value_if_false

d) if condition: value_if_true, value_if_false

4)Which of the following is an example of a nested if statement in Python? a)

a)
if x > y:
    if x > z:
        print("x is the largest")
b)if x > y:
    print("x is greater than y")
elif y > x:
    print("y is greater than x")
c)for i in range(10):
    if i == 5:
        print("Loop is over")
        break
    else:
        print(i)
d) None of the above

Answers:

c) if
a)if condition:
    # code to execute if condition is true
else:
    # code to execute if condition is false
Here's another quiz for you:

Which keyword is used to begin an if statement in Python?
a) for
b) while
c) if
d) switch

What is the syntax for an if-else statement in Python?
a)

sql
Copy code
if condition:
    # code to execute if condition is true
else:
    # code to execute if condition is false
b)

sql
Copy code
if condition:
    # code to execute if condition is true
elif condition2:
    # code to execute if condition2 is true
else:
    # code to execute if both condition and condition2 are false
c)

sql
Copy code
if condition:
    # code to execute if condition is true
    else:
    # code to execute if condition is false
d)

sql
Copy code
if condition:
    # code to execute if condition is true
    elif condition2:
    # code to execute if condition2 is true
    else:
    # code to execute if both condition and condition2 are false
What is the purpose of a break statement in a loop?
a) To end the current iteration of the loop and move on to the next iteration
b) To exit the loop completely
c) To skip over a certain number of iterations in the loop
d) None of the above

What is the syntax for a shorthand if statement in Python?
a) condition ? value_if_true : value_if_false
b) condition if value_if_true else value_if_false
c) if condition: value_if_true else: value_if_false
d) if condition: value_if_true, value_if_false

Which of the following is an example of a nested if statement in Python?
a)

python
Copy code
if x > y:
    if x > z:
        print("x is the largest")
b)

python
Copy code
if x > y:
    print("x is greater than y")
elif y > x:
    print("y is greater than x")
c)

python
Copy code
for i in range(10):
    if i == 5:
        print("Loop is over")
        break
    else:
        print(i)
d) None of the above

Answers:

c) if
a)
sql
Copy code
if condition:
    # code to execute if condition is true
else:
    # code to execute if condition is false
b) To exit the loop completely
b) condition if value_if_true else value_if_false
a)if x > y:
    if x > z:
        print("x is the largest")