View source for Conditional Statements (if, else if, else, switch)

=== 3.3.1 Conditional Statements (if, else if, else, switch) ===
Imagine you're at a crossroads, and you need to decide which way to go. Your decision depends on a condition, like "If the sign says 'Beach', go left. Otherwise, go straight."

'''Conditional Statements''' are programming instructions that allow your program to '''make decisions''' based on whether a certain condition is true or false. They let your code choose different paths of execution.

Here are the main types of conditional statements:

* '''if statement:'''
** This is the simplest decision-maker. It says: '''"IF a condition is true, THEN do this specific action."'''
** If the condition is false, the action is skipped.

'''Example:'''

<code>IF (it is raining) THEN</code>

<code>   Take an umbrella.</code>

<code>In code:</code>

<code>weather = "raining"</code>

<code>if weather == "raining":</code>

<code>   print("Take an umbrella.")</code>

* '''if-else statement:'''
** This gives your program two options. It says: '''"IF a condition is true, THEN do this action. ELSE (otherwise), do that different action."'''
** Only one of the two actions will ever happen.

'''Example:'''

<code>IF (you are hungry) THEN</code>

<code>   Eat a snack.</code>

<code>ELSE</code>

<code>   Go play outside.</code>

<code>In code:</code>

<code>is_hungry = True</code>

<code>if is_hungry:</code>

<code>   print("Eat a snack.")</code>

<code>else:</code>

<code>   print("Go play outside.")</code>

* '''if-else if-else (or elif in Python) statement:'''
** This allows your program to check '''multiple conditions''' in order. It says: '''"IF condition 1 is true, do this. ELSE IF condition 2 is true, do that. ELSE (if none of the above are true), do something else."'''
** The computer checks each condition one by one. As soon as it finds a true condition, it performs that action and then skips all the other else if and else parts.

'''Example:'''

<code>IF (grade is A) THEN</code>

<code>   You get a gold star!</code>

<code>ELSE IF (grade is B) THEN</code>

<code>   You get a silver star!</code>

<code>ELSE</code>

<code>   Keep trying!</code>

In code (Python example):

<code>grade = "B"</code>

<code>if grade == "A":</code>

<code>   print("You get a gold star!")</code>

<code>elif grade == "B": # Only checked if grade is NOT "A"</code>

<code>   print("You get a silver star!")</code>

<code>else: # Only runs if grade is NOT "A" and NOT "B"</code>

<code>   print("Keep trying!")</code>

* '''switch statement (in languages like Java, C++, C#):'''
** This is a special type of conditional statement used when you have '''many possible exact values''' for a single variable, and you want to do different things for each value.
** It's like having a menu: "Choose option 1 for pizza, option 2 for pasta, option 3 for salad."
** It's often cleaner than a long chain of if-else if statements when checking for exact matches.

'''Example (Java concept):'''

<code>// Imagine 'dayOfWeek' is a number from 1 (Monday) to 7 (Sunday)</code>

<code>switch (dayOfWeek) {</code>

<code>   case 1:</code>

<code>       System.out.println("It's Monday!");</code>

<code>       break; // Stop here</code>

<code>   case 5:</code>

<code>       System.out.println("It's Friday!");</code>

<code>       break;</code>

<code>   default: // If dayOfWeek is none of the above</code>

<code>       System.out.println("It's a weekday or weekend.");</code>

<code>}</code>

* (Note: Python does not have a direct switch statement, but uses if-elif-else or dictionaries for similar logic.)

Conditional statements are essential for making programs smart and able to respond differently to different situations.

'''Bibliography:'''

* '''W3Schools - Python If...Else''': https://www.w3schools.com/python/python_conditions.asp
* '''GeeksforGeeks - Conditional Statements in C/C++''': https://www.geeksforgeeks.org/cpp/decision-making-c-cpp/
* '''Wikipedia - Conditional (computer programming)''': 
[[wikipedia:Conditional_(computer_programming|https://en.wikipedia.org/wiki/Conditional_(computer_programming)]])