Operators in C++

#include <iostream>
using namespace std;

int main() {
    int a = 17, b = 5;

    cout << "a + b = " << a + b << endl;   // 22
    cout << "a - b = " << a - b << endl;   // 12
    cout << "a * b = " << a * b << endl;   // 85
    cout << "a / b = " << a / b << endl;   // 3 (integer division)
    cout << "a % b = " << a % b << endl;   // 2 (remainder)

    // Float division vs int division
    cout << "17 / 5 (int): " << 17 / 5 << endl;          // 3
    cout << "17.0 / 5 (double): " << 17.0 / 5 << endl;   // 3.4

    // Modulus with negatives (C++11 guaranteed)
    cout << "-7 % 3 = " << -7 % 3 << endl;    // -1
    cout << "7 % -3 = " << 7 % -3 << endl;    // 1
    cout << "-7 % -3 = " << -7 % -3 << endl;  // -1

    return 0;
}

#include <iostream>
using namespace std;

int main() {
    int x = 5;
    int a = ++x;  // Pre: increment first, then assign
    cout << "After ++x: x=" << x << ", a=" << a << endl;  // x=6, a=6

    int y = 5;
    int b = y++;  // Post: assign first, then increment
    cout << "After y++: y=" << y << ", b=" << b << endl;  // y=6, b=5

    // In a standalone statement, both are identical
    int m = 10;
    m++;  // m becomes 11
    ++m;  // m becomes 12
    cout << "m = " << m << endl;

    // Pre-decrement and post-decrement
    int p = 10;
    cout << "--p = " << --p << endl;  // 9
    cout << "p-- = " << p-- << endl;  // 9 (prints current, then decrements)
    cout << "p   = " << p << endl;    // 8

    return 0;
}

#include <iostream>
using namespace std;

int main() {
    int a = 5;  // 0101 in binary
    int b = 3;  // 0011 in binary

    cout << "a & b  = " << (a & b) << endl;   // 0001 = 1 (AND)
    cout << "a | b  = " << (a | b) << endl;   // 0111 = 7 (OR)
    cout << "a ^ b  = " << (a ^ b) << endl;   // 0110 = 6 (XOR)
    cout << "~a     = " << (~a) << endl;       // -6 (bitwise NOT)
    cout << "a << 1 = " << (a << 1) << endl;  // 1010 = 10 (left shift)
    cout << "a >> 1 = " << (a >> 1) << endl;  // 0010 = 2 (right shift)

    // Useful bitwise tricks
    int n = 12;
    cout << "\n--- Bitwise Tricks ---" << endl;
    cout << "Check if " << n << " is even: " << ((n & 1) == 0) << endl;
    cout << "Multiply " << n << " by 4: " << (n << 2) << endl;
    cout << "Divide " << n << " by 2: " << (n >> 1) << endl;

    // XOR swap
    int x = 10, y = 20;
    x ^= y;
    y ^= x;
    x ^= y;
    cout << "After XOR swap: x=" << x << ", y=" << y << endl;

    return 0;
}

#include <iostream>
using namespace std;

int main() {
    int a = 5, b = 0;

    cout << "a && b: " << (a && b) << endl;   // 0 (5 is true, 0 is false)
    cout << "a || b: " << (a || b) << endl;   // 1 (5 is true)
    cout << "!a: " << (!a) << endl;            // 0 (not true = false)
    cout << "!b: " << (!b) << endl;            // 1 (not false = true)

    // Short-circuit demonstration
    int x = 0;
    bool result = (x != 0) && (10 / x > 1);  // Safe! 10/x never executes
    cout << "Short-circuit AND: " << result << endl;

    int y = 5;
    bool result2 = (y > 0) || (10 / 0 > 1);  // Safe! 10/0 never executes
    cout << "Short-circuit OR: " << result2 << endl;

    // Truthiness: any non-zero is true
    cout << "\n(42 && -1): " << (42 && -1) << endl;    // 1 (both non-zero)
    cout << "(0 || 100): " << (0 || 100) << endl;      // 1 (100 is non-zero)

    return 0;
}

#include <iostream>
using namespace std;

int main() {
    int a = 15, b = 20;

    // Ternary operator
    int maxVal = (a > b) ? a : b;
    cout << "Max of " << a << " and " << b << ": " << maxVal << endl;

    // Ternary for absolute value
    int x = -7;
    int absX = (x >= 0) ? x : -x;
    cout << "Absolute value of " << x << ": " << absX << endl;

    // Nested ternary (readable version)
    int marks = 75;
    string grade = (marks >= 90) ? "A" :
                   (marks >= 80) ? "B" :
                   (marks >= 70) ? "C" :
                   (marks >= 60) ? "D" : "F";
    cout << "Grade for " << marks << ": " << grade << endl;

    // Comma operator
    int y = (1, 2, 3);  // y = 3 (last expression)
    cout << "Comma result: " << y << endl;

    // Comma in for loop
    for (int i = 0, j = 10; i < j; i++, j--) {
        cout << "i=" << i << " j=" << j << "  ";
    }
    cout << endl;

    return 0;
}

#include <iostream>
using namespace std;

int main() {
    // Trap 1: Bitwise vs relational precedence
    int x = 5;
    cout << "x & 1 == 0: " << (x & 1 == 0) << endl;      // Parsed as x & (1==0) = 5 & 0 = 0
    cout << "(x & 1) == 0: " << ((x & 1) == 0) << endl;    // Correct: (5 & 1) = 1, 1==0 = false

    // Trap 2: Multiplication before addition
    cout << "2 + 3 * 4 = " << 2 + 3 * 4 << endl;  // 14, not 20

    // Trap 3: Assignment in condition
    int a = 0;
    if (a = 5) {  // Assignment, not comparison! a becomes 5, condition is true
        cout << "a = 5 was assigned (truthy)" << endl;
    }

    // Trap 4: Chained comparisons do not work as expected
    int val = 5;
    // This does NOT check if 1 < val < 10
    cout << "1 < 5 < 3: " << (1 < 5 < 3) << endl;  // (true < 3) = (1 < 3) = true!
    // Correct way:
    cout << "1 < val && val < 10: " << (1 < val && val < 10) << endl;

    return 0;
}

#include <iostream>
using namespace std;

int main() {
    int x = 10;
    cout << "x = " << x << endl;

    x += 5;   // x = x + 5
    cout << "x += 5: " << x << endl;   // 15

    x -= 3;   // x = x - 3
    cout << "x -= 3: " << x << endl;   // 12

    x *= 2;   // x = x * 2
    cout << "x *= 2: " << x << endl;   // 24

    x /= 4;   // x = x / 4
    cout << "x /= 4: " << x << endl;   // 6

    x %= 4;   // x = x % 4
    cout << "x %= 4: " << x << endl;   // 2

    x <<= 3;  // x = x << 3 (multiply by 8)
    cout << "x <<= 3: " << x << endl;  // 16

    x >>= 1;  // x = x >> 1 (divide by 2)
    cout << "x >>= 1: " << x << endl;  // 8

    // sizeof as an operator
    cout << "\nsizeof(x): " << sizeof(x) << endl;
    cout << "sizeof(int): " << sizeof(int) << endl;
    cout << "sizeof(x + 1.0): " << sizeof(x + 1.0) << endl;  // double

    return 0;
}