Question

1: Imagine an alien was just shot down in a game. Create a variable called alien_color and assign it a value of 'green', 'yellow', or 'red'. \- Write an if… # Alien Colors #1: Imagine an alien was just shot down in a game. Create a variable called alien_color and assign it a value of 'green', 'yellow', or 'red'. \- Write an if statement to test whether the alien's color is green. If it is, print a message that the player just earned 5 points. \- Write one version of this program that passes the if test and another that fails. (The version that fails will have no output.)

Short answer

One version prints 'The player just earned 5 points.' with 'green'; the other prints nothing with 'red'.

Step-by-step solution

- Create the Variable

First, we need to declare and initialize a variable named `alien_color`. This variable can hold one of the strings: 'green', 'yellow', or 'red'. For this exercise, let's initially assign it the value 'green': ```python alien_color = 'green' ```

- Write the If Statement to Pass

Next, we write an if statement that checks if the value of `alien_color` is 'green'. If the condition is true, we want to print that the player just earned 5 points. The code looks like this: ```python if alien_color == 'green': print('The player just earned 5 points.') ``` In this case, since `alien_color` is 'green', the condition evaluates to true and we should see the message printed.

- Change the Variable to Fail

We now create a version where the if statement fails by changing the `alien_color` to a value that is not 'green'. For instance, we can set it to 'red': ```python alien_color = 'red' ``` Then the same if statement is used: ```python if alien_color == 'green': print('The player just earned 5 points.') ``` Since `alien_color` is 'red', the condition is false and no message will be printed.

Key concepts

if statements

In Python, an `if statement` is a fundamental control structure used to make decisions in your programs. It allows you to execute a block of code only if a specified condition is met. The basic syntax of an `if statement` includes the keyword `if`, followed by a condition, and a colon. The subsequent lines, indented, contain the code block to run if the condition is true.
For example, in our Alien Colors exercise, we used an `if statement` to check if `alien_color` is equal to `'green'`. This is done using the equality operator `==`, which returns `True` if the operands are equal.

• If the color is green, a message saying the player earned points is printed.
• If the condition fails, the indented block does not run, resulting in no output.

Using `if statements` effectively enables you to control the flow of your program and respond dynamically to different inputs and conditions.

variables

In the realm of programming, a `variable` is essentially a storage location, identified by a name, that holds data. In Python, variables are highly versatile and can store different data types, such as strings, numbers, and lists.
They are central to programming as they help keep track of data throughout the execution of a program.
For the Alien Colors example:

• We created a `variable` called `alien_color` and assigned it a string value.
• This variable holds the color of the alien, which can be `'green'`, `'yellow'`, or `'red'`.

By abstracting our data in variables, we can easily modify our code and adapt it to different conditions without rewriting all our statements.

conditional logic

Conditional logic is the tool that allows programs to make decisions and execute specific blocks of code based on certain conditions. It is a cornerstone of any programming language and is usually implemented with `if` statements.
By using conditional logic, we instruct the program to decide what actions to take. This has broad applications. In our example:

• The condition `alien_color == 'green'` determines whether the program prints a message.
• Conditional logic checks boolean expressions, evaluating them as either `True` or `False`.

This means that depending on the value of `alien_color`, different outcomes can occur. The ability to introduce complex, multi-branched decision making makes conditional logic indispensable for writing dynamic and interactive programs.