Question

What statement do you use in Python to write a dual alternative decision structure?

Short answer

Answer: The "if-else" statement is used in Python to create a dual alternative decision structure. This allows the code to follow one path when a condition is met (True) and another path when the condition is not met (False). The syntax for the basic if-else statement is: ``` if condition: # Execute this block of code when the condition is True else: # Execute this block of code when the condition is False ```

Step-by-step solution

Understand if-else statement in Python

The "if-else" statement in Python is used to create a dual alternative decision structure. This statement allows the code to follow one path when a condition is met (True) and another path when the condition is not met (False).

Write the syntax for if-else statement in Python

The syntax for the basic if-else statement in Python is as follows: ``` if condition: # Execute this block of code when the condition is True else: # Execute this block of code when the condition is False ``` The "condition" can be any logical or comparison expression that evaluates to either True or False.

Key concepts

If-Else Statements

In Python programming, the "if-else" statement is a fundamental concept used to control the flow of your code. It allows your program to make decisions based on specific conditions. This is what's known as a dual alternative decision structure.
When you write an if-else statement, you give your code two possible pathways.

• If the specified condition evaluates to True, the first block of code will execute.
• On the other hand, if the condition evaluates to False, the code inside the else block will run.

This ability to select different code segments based on conditions is what makes "if-else" a powerful tool in programming.

Decision Structures

Decision structures are essential in programming because they allow you to control how your program executes based on dynamic conditions. In Python, a common decision structure is the if-else statement. It enables a choice between two different actions, depending on whether a condition is true or false.
Using decision structures effectively requires understanding the conditions under which each block of code should run. This keeps your program running smoothly and as intended.

• Decision structures help to handle situations where the program must make a choice.
• They make code more flexible and capable of responding to different inputs and scenarios.

Without decision structures, code would simply run in a linear fashion, executing the same steps every time, regardless of the situation.

Logical Expressions

Logical expressions are used in programming to form conditions that control decision structures like "if-else" statements. They are expressions that result in a Boolean value: True or False.
Logical operators like "and", "or", and "not" can combine multiple expressions.

• "and" returns True if all expressions are true.
• "or" returns True if at least one expression is true.
• "not" inverts the truth value of an expression.

By understanding logical expressions and operators, you can create complex conditions that allow for sophisticated decision-making processes in your code.

Comparison Expressions

Comparison expressions in Python evaluate how two values relate to each other. They are crucial in creating conditions within decision structures like if-else statements.
These expressions return a Boolean value, True or False, based on the comparison.

• The "==" operator checks if values are equal.
• The "!=" operator checks if values are not equal.
• "<", "<=", ">", and ">=" compare values based on size or order.

By mastering comparison expressions, you can write precise conditions to guide your program's flow and make informed decisions, enhancing the functionality and adaptability of your code.