> ## Documentation Index
> Fetch the complete documentation index at: https://programming-for-career.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Conditional Statements in C++

> Learn about conditional statements in C++, including if, if-else, if-else-if ladder, nested if, switch, and ternary operator.

## Introduction

Conditional statements allow a program to make decisions based on certain conditions. In real life, we make decisions every day:

* "If it's raining, take an umbrella."
* "If my phone battery is low, charge it."

Similarly, in C++, conditional statements control the flow of execution based on conditions.

## Types of Conditional Statements

1. **if statement**
2. **if-else statement**
3. **if-else-if ladder**
4. **nested if statements**
5. **switch statement**
6. **ternary operator**

## 1. The `if` Statement

The `if` statement executes a block of code only if a specified condition is `true`.

### Example:

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    int temperature;
    cout << "Enter the temperature: ";
    cin >> temperature;

    if (temperature > 30) {
        cout << "It's a hot day. Stay hydrated!" << endl;
    }
    return 0;
}
```

### Explanation:

* If `temperature` is greater than 30, the message is displayed.
* Otherwise, nothing happens.

### Real-Life Analogy:

Imagine checking the weather before going outside:

* **Condition:** If it's sunny (`temperature > 30`), wear sunglasses.
* **Code Execution:** Only applies when the condition is true.

## 2. The `if-else` Statement

An `if-else` statement executes one block of code if the condition is `true`, and another block if it is `false`.

### Example:

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    int age;
    cout << "Enter your age: ";
    cin >> age;

    if (age >= 18) {
        cout << "You are eligible to vote." << endl;
    } else {
        cout << "You are not eligible to vote yet." << endl;
    }
    return 0;
}
```

### Real-Life Analogy:

* **Condition:** If you're **18 or older**, you can vote.
* **Else:** You must wait until you're eligible.

## 3. The `if-else-if` Ladder

Used when there are multiple conditions to check.

### Example:

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    int marks;
    cout << "Enter your marks: ";
    cin >> marks;

    if (marks >= 90) {
        cout << "Grade: A+" << endl;
    } else if (marks >= 80) {
        cout << "Grade: A" << endl;
    } else if (marks >= 70) {
        cout << "Grade: B" << endl;
    } else {
        cout << "Grade: C" << endl;
    }
    return 0;
}
```

### Explanation:

* If `marks` is **90 or more**, print `A+`.
* If `marks` is **80-89**, print `A`.
* If `marks` is **70-79**, print `B`.
* Otherwise, print `C`.

### Real-Life Analogy:

* Schools assign grades based on scores.
* Each range maps to a different grade.

### Example: Traffic Light System 🚦

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    string signal;
    cout << "Enter the traffic light color (red/yellow/green): ";
    cin >> signal;

    if (signal == "red") {
        cout << "Stop!" << endl;
    } else if (signal == "yellow") {
        cout << "Slow down!" << endl;
    } else if (signal == "green") {
        cout << "Go!" << endl;
    } else {
        cout << "Invalid input. Please enter red, yellow, or green." << endl;
    }
    return 0;
}
```

### Explanation:

* The program asks for a traffic light color.
* `if` checks if it's red → outputs "Stop!".
* `else if` checks if it's yellow → outputs "Slow down!".
* `else if` checks if it's green → outputs "Go!".
* `else` handles incorrect inputs.

## 4. Nested `if` Statements

One `if` inside another. Used when conditions depend on previous ones.

### Example:

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    int year;
    cout << "Enter a year: ";
    cin >> year;

    if (year % 4 == 0) {
        if (year % 100 != 0 || year % 400 == 0) {
            cout << year << " is a leap year." << endl;
        } else {
            cout << year << " is not a leap year." << endl;
        }
    } else {
        cout << year << " is not a leap year." << endl;
    }
    return 0;
}
```

### Real-Life Analogy:

* A store offers discounts only if:
  * You're a **member** (checked first).
  * If **premium member**, you get **extra discount**.

## 5. The `switch` Statement

`switch` is used when multiple values need to be compared to a single variable.

### Example:

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    int day;
    cout << "Enter a day number (1-7): ";
    cin >> day;

    switch (day) {
        case 1: cout << "Sunday" << endl; break;
        case 2: cout << "Monday" << endl; break;
        case 3: cout << "Tuesday" << endl; break;
        case 4: cout << "Wednesday" << endl; break;
        case 5: cout << "Thursday" << endl; break;
        case 6: cout << "Friday" << endl; break;
        case 7: cout << "Saturday" << endl; break;
        default: cout << "Invalid day!" << endl;
    }
    return 0;
}
```

### Example: Restaurant Menu 🍽️

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    int choice;
    cout << "Choose an item:\n1. Pizza\n2. Burger\n3. Pasta\n";
    cin >> choice;

    switch (choice) {
        case 1:
            cout << "You chose Pizza." << endl;
            break;
        case 2:
            cout << "You chose Burger." << endl;
            break;
        case 3:
            cout << "You chose Pasta." << endl;
            break;
        default:
            cout << "Invalid choice!" << endl;
    }
    return 0;
}
```

### Explanation:

* The program presents a menu with options.
* `switch` evaluates `choice` and executes the corresponding `case` block.
* `break` prevents the execution of the next case.
* `default` handles invalid inputs.

### When to Use `switch`?

* When comparing a single variable against multiple constant values.
* When `if-else` makes the code lengthy.

## 6. The Ternary Operator

The ternary operator (`? :`) is a shorthand for `if-else`.

### Example:

```cpp theme={null}
#include <iostream>
using namespace std;

int main() {
    int number;
    cout << "Enter a number: ";
    cin >> number;

    string result = (number % 2 == 0) ? "Even" : "Odd";
    cout << "The number is " << result << endl;

    return 0;
}
```

### Real-Life Analogy:

* Instead of writing:
  ```cpp theme={null}
  if (age >= 18) {
      cout << "Adult";
  } else {
      cout << "Minor";
  }
  ```
* You can write: `cout << (age >= 18 ? "Adult" : "Minor");`

## When to Use Which?

| Scenario                              | Use                |
| ------------------------------------- | ------------------ |
| Checking a single condition           | `if`               |
| Two possibilities (true/false)        | `if-else`          |
| Multiple conditions                   | `if-else-if`       |
| Nested conditions                     | `nested if`        |
| Checking one value against many cases | `switch`           |
| Simple if-else in one line            | `ternary operator` |

## Conclusion

Conditional statements allow programs to make decisions. We covered:

* `if` statements for basic conditions.
* `if-else` for two outcomes.
* `if-else-if` for multiple choices.
* `nested if` for dependent conditions.
* `switch` for multiple exact matches.
* Ternary operator for concise conditions.

Mastering these is crucial for writing interactive and intelligent C++ programs!

### Up Next: Loops in C++