Day 4 / 100 (C++)

August 19, 2025

This content originally appeared on DEV Community and was authored by Munin Borah

What I Learned

1. Float Data Type

float is used for decimal numbers (like 3.14, 0.99, -12.5).
Compared to int, floats allow precision, but not always exact precision (because computers store them in binary).

Example:

float pi = 3.14;
cout << pi << endl;   // prints 3.14

Key insight: Use float (or even better, double) when you need fractional values. Use int when you only need whole numbers.

2. Increment (`++`) and Decrement (`--`) Operators

These operators let you quickly increase or decrease a variable’s value by 1.

Increment: x++ is the same as x = x + 1
Decrement: x-- is the same as x = x - 1

There are two types:

Post-increment (x++) → use the current value, then increase.
Pre-increment (++x) → increase first, then use the new value.

Example:

int x = 5;

cout << x++ << endl;  // prints 5, then x becomes 6
cout << ++x << endl;  // x becomes 7 first, then prints 7

Key insight: If you just want to add/subtract, both work. But if you’re using it in a more complex expression, pre vs post matters.

Example Code

#include <iostream>
using namespace std;

int main() {
    // Working with float
    float price = 9.99;
    cout << "Price: " << price << endl;

    // Increment & Decrement
    int counter = 10;

    cout << "Counter: " << counter << endl;  // 10
    counter++;   // increase by 1
    cout << "After counter++: " << counter << endl;  // 11

    counter--;   // decrease by 1
    cout << "After counter--: " << counter << endl;  // 10

    // Pre vs Post increment
    cout << "Post-increment: " << counter++ << endl;  // prints 10, then counter = 11
    cout << "Pre-increment: " << ++counter << endl;  // counter = 12, then prints 12

    return 0;
}

Takeaway

Float vs Int: Use float for decimals, int for whole numbers.
Increment & Decrement: Shortcuts for adding/subtracting 1.
Pre vs Post increment: Order matters only when used inside expressions.

At the start, it felt tough, but it’s getting smoother now. Learning may be slow, but consistency wins the game.

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