📅 Date: Jan 3, 2026
🔥 Topic: Conditionals (If, Else If, Else)

🤔 What are Conditionals?

Up until now, my code ran line-by-line, from top to bottom. But in real life, we make decisions based on situations.

"If it rains, take an umbrella. Else, wear sunglasses."

In C++, we use Control Flow statements to do this. The program evaluates a condition: if it's true, it runs a specific block of code; if false, it skips it.

🚦 The Syntax

The structure is very similar to English: 

if (condition) {
    // Runs if condition is TRUE
} 
else if (another_condition) {
    // Runs if the first was FALSE, but this one is TRUE
} 
else {
    // Runs if ALL above conditions were FALSE
}

⚖️ Comparison Operators

To make conditions, we need to compare things using these operators:

  • == : Equals to (Don't confuse with = assignment!)
  • != : Not Equals to
  • >, < : Greater than, Less than
  • >=, <= : Greater/Less than or Equal to

💻 Day 3 Code: The Grading System

To practice this, I built a simple Grading System. It takes the student's marks as input and decides the grade logic. 

#include <iostream>
using namespace std;

int main() {
    int marks;
    
    cout << "Enter your marks (0-100): ";
    cin >> marks;

    // The Logic Ladder
    if (marks >= 90) {
        cout << "Result: Grade A (Excellent!)" << endl;
    } 
    else if (marks >= 75) {
        cout << "Result: Grade B (Good)" << endl;
    } 
    else if (marks >= 40) {
        cout << "Result: Grade C (Passed)" << endl;
    } 
    else {
        // If none of the above are true
        cout << "Result: Fail (Needs Improvement)" << endl;
    }

    return 0;
}

🧩 Logical Operators (The Combo Moves)

Sometimes we need to check two things at once. I also learned about Logical Operators:

  • && (AND): Both conditions must be true.
    Example: if (age > 18 && hasID)
  • || (OR): At least one condition must be true.
  • ! (NOT): Reverses the result.

💭 Thoughts

The power of code lies in logic. Today, I learned how to control the flow of the program. The most common mistake I made was confusing = (assign value) with == (compare value).

Tomorrow, I will tackle Loops (For & While) to repeat tasks without rewriting code.