Python3 – if , if..else, Nested if, if-elif statements

There are situations in real life when we need to do some specific task and based on some specific conditions, we decide what we should do next. Similarly, there comes a situation in programming where a specific task is to be performed if a specific condition is True. In such cases, conditional statements can be used. The following are the conditional statements provided by Python. 

1. if
2. if..else
3. Nested if
4. if-elif statements.

Let us go through all of them. 

if Statement in Python

If the simple code of block is to be performed if the condition holds true then the if statement is used. Here the condition mentioned holds then the code of the block runs otherwise not.

Python if Statement Syntax

Syntax: if condition:

# Statements to execute if

# condition is true

Flowchart of if Statement in Python

Below is the flowchart by which we can understand how to use if statement in Python:

Example: Basic Conditional Check with if Statement

In this example, an if statement checks if 10 is greater than 5. If true, it prints “10 greater than 5”; regardless, it then prints “Program ended” as the next statement, indicating the program flow.

# if statement example
if 10 > 5:
    print("10 greater than 5")

print("Program ended")

10 greater than 5
Program ended

Indentation(White space) is used to delimit the block of code. As shown in the above example it is mandatory to use indentation in Python3 coding.

if else Statement in Python

In conditional if Statement the additional block of code is merged as else statement which is performed when if condition is false. 

Python if-else Statement Syntax  

Syntax: if (condition): # Executes this block if # condition is trueelse: # Executes this block if # condition is false

Flow Chart of if-else Statement in Python

Below is the flowchart by which we can understand how to use if-else statement in Python:

Example 1: Handling Conditional Scenarios with if-else

In this example, the code assigns the value 3 to variable x and uses an if..else statement to check if x is equal to 4. If true, it prints “Yes”; otherwise, it prints “No,” demonstrating a conditional branching structure.

# if..else statement example
x = 3
if x == 4:
    print("Yes")
else:
    print("No")

No

Example 2: Nested if..else Chain for Multiple Conditions

You can also chain if..else statement with more than one condition. In this example, the code uses a nested if..else chain to check the value of the variable letter. It prints a corresponding message based on whether letter is “B,” “C,” “A,” or none of the specified values, illustrating a hierarchical conditional structure.

# if..else chain statement
letter = "A"

if letter == "B":
    print("letter is B")

else:

    if letter == "C":
        print("letter is C")

    else:

        if letter == "A":
            print("letter is A")

        else:
            print("letter isn't A, B and C")

letter is A

Nested if Statement

if statement can also be checked inside other if statement. This conditional statement is called a nested if statement. This means that inner if condition will be checked only if outer if condition is true and by this, we can see multiple conditions to be satisfied.

Python Nested If Statement Syntax

Syntax: if (condition1): # Executes when condition1 is true if (condition2): # Executes when condition2 is true # if Block is end here# if Block is end here

Flow chart of Nested If Statement In Python

Below is the flowchart by which we can understand how to use nested if statement in Python:

Example: Managing Nested Conditions for Refined Control

In this example, the code uses a nested if statement to check if the variable num is greater than 5. If true, it further checks if num is less than or equal to 15, printing “Bigger than 5” and “Between 5 and 15” accordingly, showcasing a hierarchical condition for refined control flow.

# Nested if statement example
num = 10

if num > 5:
    print("Bigger than 5")

    if num <= 15:
        print("Between 5 and 15")

Bigger than 5
Between 5 and 15

if-elif Statement in Python

The if-elif statement is shortcut of if..else chain. While using if-elif statement at the end else block is added which is performed if none of the above if-elif statement is true.

Python if-elif Statement Syntax:-  

Syntax: if (condition): statementelif (condition): statement..else: statement

Flow Chart of Python if-elif Statement

Below is the flowchart by which we can understand how to use elif in Python:

Example: Sequential Evaluation with if-elif-else Structure

In this example, the code uses an if-elif-else statement to evaluate the value of the variable letter. It prints a corresponding message based on whether letter is “B,” “C,” “A,” or none of the specified values, demonstrating a sequential evaluation of conditions for controlled branching.

# if-elif statement example
letter = "A"

if letter == "B":
    print("letter is B")

elif letter == "C":
    print("letter is C")

elif letter == "A":
    print("letter is A")

else:
    print("letter isn't A, B or C")

letter is A

Can We Use Elif in Nested If?

Yes, you can use elif within nested if statements in Python. This allows for more complex decision structures within a branch of another decision. For example:

python
Copy code
x = 10
y = 5
if x > 5:
    if y > 5:
        print("x and y are greater than 5")
    elif y == 5:
        print("x is greater than 5 and y is 5")
    else:
        print("x is greater than 5 and y is less than 5")

This structure provides conditional checks within another conditional check, enhancing the decision-making capabilities of your code.

Are You Allowed to Nest If Statements Inside Other If Statements in Python?

Yes, you are allowed to nest if statements inside other if statements in Python. This is a common practice used to make more complex conditional logic possible. Nested if statements can be as deep as you need, although deep nesting can make your code harder to read and maintain.

Python3 – if , if..else, Nested if, if-elif statements – FAQs

Can We Use Multiple If Instead of Elif?

Yes, you can use multiple if statements instead of elif, but the behavior of your code will change. elif allows for mutually exclusive conditions; only one branch can execute. With multiple if statements, each if condition is checked independently of others, so multiple branches might execute.

Example:

x = 10
y = 5
if x > 5:
    if y > 5:
        print("x and y are greater than 5")
    elif y == 5:
        print("x is greater than 5 and y is 5")
    else:
        print("x is greater than 5 and y is less than 5")

Using elif, the second condition would only be checked if the first condition failed.

What is the Difference Between if-else and Nested If Statements in Python?

• if-else: Refers to a simple conditional structure where if a condition is true, the if block executes; otherwise, the else block executes. There is only one alternative path.
• Nested if statements: Involve placing one or more if or if-else structures inside another if or else block. This setup is used to test for further conditions after a previous condition has been found to be true.

What is the Maximum Number of Elif Clauses You Can Have in a Conditional?

Python does not explicitly limit the number of elif clauses you can have after an if statement. The practical limit is generally dictated by the readability and complexity of your code. Technically, you could have hundreds or even thousands, but this would be poor practice in terms of code clarity and maintainability. If you find yourself using many elif statements, consider refactoring your code, possibly using a different data structure like a dictionary to map conditions to functions or outcomes, or using a different logic flow altogether.

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