Here are detailed examples of if, if-else, and if-else-if statements in C++ with explanations and outputs.

1️⃣ If Statement in C++

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

🔹 Syntax

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

✅ Example

#include <iostream>
using namespace std;

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

    if (num > 0) {
        cout << "The number is positive." << endl;
    }

    cout << "End of program." << endl;
    return 0;
}

🔹 Output (if input is 5)

Enter a number: 5
The number is positive.
End of program.

🔹 Output (if input is -3)

Enter a number: -3
End of program.

🚀 Explanation:

  • The condition num > 0 is checked.
  • If true, the message "The number is positive." is printed.
  • If false, the program moves on without printing anything.

2️⃣ If-Else Statement in C++

The if-else statement runs one block of code if the condition is true, and another block if it is false.

🔹 Syntax

if (condition) {
    // Code if condition is true
} else {
    // Code if condition is false
}

✅ Example

#include <iostream>
using namespace std;

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

    if (num % 2 == 0) {
        cout << "The number is even." << endl;
    } else {
        cout << "The number is odd." << endl;
    }

    return 0;
}

🔹 Output (if input is 4)

Enter a number: 4
The number is even.

🔹 Output (if input is 7)

Enter a number: 7
The number is odd.

🚀 Explanation:

  • The condition num % 2 == 0 checks if the number is even.
  • If true, "The number is even." is printed.
  • If false, "The number is odd." is printed.

3️⃣ If-Else-If Statement in C++

The if-else-if ladder allows checking multiple conditions.

🔹 Syntax

if (condition1) {
    // Code if condition1 is true
} else if (condition2) {
    // Code if condition2 is true
} else {
    // Code if none of the above conditions are true
}

✅ Example

#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 >= 75) {
        cout << "Grade: B" << endl;
    } else if (marks >= 50) {
        cout << "Grade: C" << endl;
    } else {
        cout << "Grade: F (Fail)" << endl;
    }

    return 0;
}

🔹 Output (if input is 88)

Enter your marks: 88
Grade: B

🔹 Output (if input is 40)

Enter your marks: 40
Grade: F (Fail)

🚀 Explanation:

  • If marks >= 90, it prints "Grade: A".
  • Else, if marks >= 75, it prints "Grade: B".
  • Else, if marks >= 50, it prints "Grade: C".
  • Otherwise, it prints "Grade: F".

📌 Summary

✔ if Statement → Executes a block only if a condition is true.
✔ if-else Statement → Runs one block if true, another if false.
✔ if-else-if Ladder → Checks multiple conditions in sequence.

Would you like more examples on nested if statements or switch statements? 🚀