Mini Programming: Day 7 - Mastering Conditional Statements and Logical Operators156

Welcome back to Mini Programming! We've covered variables, data types, and basic input/output. Today, we're diving into a crucial aspect of programming: conditional statements and logical operators. These are the building blocks that allow your programs to make decisions and respond dynamically to different situations. Without them, your programs would be like a rigid, inflexible machine, incapable of adapting to changing circumstances.

Conditional Statements: The Power of Choice

Conditional statements determine the flow of execution in your program based on whether certain conditions are true or false. The most common type is the `if` statement. Let's explore its syntax and usage:

if (condition) {
// Code to execute if the condition is true
}

The `condition` is an expression that evaluates to either `true` or `false`. If the condition is true, the code within the curly braces `{}` is executed. Otherwise, it's skipped. Let's illustrate with a simple example:

int age = 20;
if (age >= 18) {
("You are an adult.");
}

In this example, the condition `age >= 18` is true because `age` is 20. Therefore, the message "You are an adult." will be printed to the console. If `age` were 15, the condition would be false, and the code inside the `if` block would be ignored.

Adding `else` for Alternative Actions

We can extend the `if` statement with an `else` block to specify what should happen if the condition is false:

int age = 15;
if (age >= 18) {
("You are an adult.");
} else {
("You are a minor.");
}

Now, if `age` is less than 18, the message "You are a minor." will be printed.

`else if` for Multiple Conditions

What if we need to handle multiple conditions? We can use `else if` to chain multiple conditions together:

int score = 85;
if (score >= 90) {
("A");
} else if (score >= 80) {
("B");
} else if (score >= 70) {
("C");
} else {
("F");
}

This code assigns letter grades based on the `score`. The conditions are checked sequentially. Once a condition is met, the corresponding code is executed, and the rest of the `else if` and `else` blocks are skipped.

Logical Operators: Combining Conditions

Logical operators allow us to combine multiple conditions into more complex expressions. The most common ones are:
`&&` (AND): Both conditions must be true for the overall expression to be true.
`||` (OR): At least one condition must be true for the overall expression to be true.
`!` (NOT): Reverses the truth value of a condition (true becomes false, and vice versa).

Example:

int age = 22;
boolean hasLicense = true;
if (age >= 18 && hasLicense) {
("You can drive.");
}

This code checks if the person is at least 18 years old AND has a driver's license. Both conditions must be true for the message to be printed.

Another example using OR:

int temperature = 25;
boolean isRainy = true;
if (temperature > 30 || isRainy) {
("Stay indoors.");
}

This code suggests staying indoors if the temperature is above 30 degrees OR it's raining.

Nested Conditional Statements

You can place conditional statements inside other conditional statements, creating nested structures. This allows for more complex decision-making processes:

int age = 15;
boolean isStudent = true;
if (age < 18) {
if (isStudent) {
("You are a minor student.");
} else {
("You are a minor.");
}
} else {
("You are an adult.");
}

This example demonstrates a nested `if` statement, providing a more nuanced response based on age and student status.

Practice Exercises

1. Write a program that checks if a number is even or odd.

2. Write a program that determines the largest of three numbers.

3. Write a program that simulates a simple calculator (addition, subtraction, multiplication, division) based on user input.

4. Write a program that checks if a year is a leap year.

Mastering conditional statements and logical operators is a fundamental step in becoming a proficient programmer. Practice these concepts thoroughly, and you'll be well-equipped to build more complex and dynamic programs in the days to come. See you in the next lesson!

2025-06-03

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