21. Absolute Difference of Two Integers

📝 Problem

Get two integers from user and print the absolute difference between two integers.

Input Format:
Accept two integers as input

Output Format:
Print the absolute difference

Constraints:
1 ≤ N1, N2 ≤ 10^9

Sample Input 1:

78 25

Sample Output 1:

Sample Input 2:

10 20

Sample Output 2:

🎯 Understanding the abs() Function - Your First Math Library!

Why We Need abs()

When calculating the difference between two numbers, the order matters: 78 - 25 = 53, but 25 - 78 = -53. The absolute difference always gives us a positive result, regardless of order!

💡 What is abs()?

The abs() function returns the absolute value (magnitude without sign) of a number. It's part of the <cmath> library, which provides mathematical functions in C++.

1️⃣ The <cmath> Library

The <cmath> library is your toolbox for mathematical operations:

Function	Purpose	Example
`abs(x)`	Absolute value	`abs(-5)` → 5
`sqrt(x)`	Square root	`sqrt(16)` → 4
`pow(x, y)`	Power (x^y)	`pow(2, 3)` → 8
`ceil(x)`	Round up	`ceil(4.2)` → 5
`floor(x)`	Round down	`floor(4.8)` → 4

2️⃣ How abs() Works

📌 Visual Example:

// Input: 78 25
int a = 78, b = 25;

// Method 1: Manual calculation (wrong if b > a)
int diff = a - b;  // 53 ✓ (works)

// What if a = 25, b = 78?
diff = a - b;  // -53 ✗ (negative!)

// Method 2: Using abs() (always correct!)
int diff = abs(a - b);  // Always positive!
// Works for both: abs(78-25)=53 and abs(25-78)=53

3️⃣ Important: abs() vs abs() - Type Matters!

                            ⚠️ Pro Tip: C++ has different abs functions for different types:
                            abs(int) - From <cstdlib> (for integers)
fabs(double) - From <cmath> (for floating-point)
labs(long) - From <cstdlib> (for long integers)

                        

For this problem with integers, abs() works perfectly. Including <cmath> gives you access to all mathematical functions at once!

4️⃣ Real-World Applications

Absolute difference is used in:

Distance calculations - Finding the gap between two points
Error measurements - Comparing predicted vs actual values
Temperature changes - Calculating temperature drops/rises
Financial analysis - Computing price differences

🚀 Try This Challenge!

After solving this problem, try modifying the code to also print which number is larger along with the difference. This will help you practice conditional statements!

💻 Solution Code

#include <iostream>
#include <cmath>

using namespace std;

int main() {
    int a, b;
    cin >> a >> b;
    cout << abs(a - b);
    return 0;
}