C++: الجمل الشرطية

if (condition) {
 // code to execute when condition is true
}

#include <iostream>

int main() {
 int num;
 std::cout << "Please enter an integer: ";
 std::cin >> num;
 
 if (num % 2 == 0) {
 std::cout << num << " is Even" << std::endl;
 }
 
 if (num % 2 != 0) {
 std::cout << num << " is Odd" << std::endl;
 }
 
 return 0;
}

Please enter an integer: 
 is Even
 is Odd

Please enter an integer: 7
7 is Odd

if (condition) {
 // execute when condition is true
} else {
 // execute when condition is false
}

#include <iostream>

int main() {
 int num;
 std::cout << "Please enter an integer: ";
 std::cin >> num;
 
 if (num % 2 == 0) {
 std::cout << num << " is Even" << std::endl;
 } else {
 std::cout << num << " is Odd" << std::endl;
 }
 
 return 0;
}

Please enter an integer: 
 is Even
 is Odd

if (num % 2 == 0)
 std::cout << "Even" << std::endl; // ✅ Only one statement, braces can be omitted
else
 std::cout << "Odd" << std::endl;

if (num % 2 == 0)
 std::cout << "Even" << std::endl;
 std::cout << "This number is divisible by 2" << std::endl; // ❌ This line always executes (indentation fooled you)

if (condition1) {
 // execute when condition1 is true
} else if (condition2) {
 // execute when condition1 is false and condition2 is true
} else if (condition3) {
 // execute when conditions 1 and 2 are false and condition3 is true
} else {
 // execute when none of the above conditions are true
}

#include <iostream>

int main() {
 int score;
 std::cout << "Please enter a score (0-100): ";
 std::cin >> score;
 
 if (score >= 90) {
 std::cout << "Excellent! Grade: A" << std::endl;
 } else if (score >= 80) {
 std::cout << "Good! Grade: B" << std::endl;
 } else if (score >= 70) {
 std::cout << "Medium! Grade: C" << std::endl;
 } else if (score >= 60) {
 std::cout << "Pass! Grade: D" << std::endl;
 } else {
 std::cout << "Not Pass! Grade: F" << std::endl;
 }
 
 return 0;
}

Please enter a score (0-100): 
Excellent! Grade: A
Good! Grade: B
Medium! Grade: C
Pass! Grade: D
Not Pass! Grade: F

Please enter a score (0-100): 85
Good! Grade: B

#include <iostream>

int main() {
 int year;
 std::cout << "Please enter a year: ";
 std::cin >> year;
 
 if (year % 400 == 0) {
 std::cout << year << " is a leap year" << std::endl;
 } else {
 if (year % 4 == 0) {
 if (year % 100 != 0) {
 std::cout << year << " is a leap year" << std::endl;
 } else {
 std::cout << year << " is not a leap year" << std::endl;
 }
 } else {
 std::cout << year << " is not a leap year" << std::endl;
 }
 }
 
 return 0;
}

Please enter a year: 
 is a leap year
 is a leap year
 is not a leap year
 is not a leap year

bool isLeapYear = (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
if (isLeapYear) {
 std::cout << year << " is a leap year" << std::endl;
} else {
 std::cout << year << " is not a leap year" << std::endl;
}

switch (expression) {
 case value1:
 // execute when expression == value1
 break;
 case value2:
 // execute when expression == value2
 break;
 ...
 default:
 // execute when none of the above match
 break;
}

#include <iostream>

int main() {
 double num1, num2;
 char op;
 
 std::cout << "Please enter the first number: ";
 std::cin >> num1;
 
 std::cout << "Please enter an operator (+ - * /): ";
 std::cin >> op;
 
 std::cout << "Please enter the second number: ";
 std::cin >> num2;
 
 switch (op) {
 case '+':
 std::cout << num1 << " + " << num2 << " = " << num1 + num2 << std::endl;
 break;
 case '-':
 std::cout << num1 << " - " << num2 << " = " << num1 - num2 << std::endl;
 break;
 case '*':
 std::cout << num1 << " * " << num2 << " = " << num1 * num2 << std::endl;
 break;
 case '/':
 if (num2 != 0) {
 std::cout << num1 << " / " << num2 << " = " << num1 / num2 << std::endl;
 } else {
 std::cout << "Error: Divisor cannot be 0!" << std::endl;
 }
 break;
 default:
 std::cout << "Error: Unsupported operator!" << std::endl;
 break;
 }
 
 return 0;
}

Please enter the first number: 
Please enter an operator (+ - * /): 
Please enter the second number: 
 +  = 
 -  = 
 *  = 
 /  = 
Error: Divisor cannot be 0!
Error: Unsupported operator!

int day = 2;

switch (day) {
 case 1:
 std::cout << "Monday" << std::endl;
 // ❌ No break, will continue to case 2
 case 2:
 std::cout << "Tuesday" << std::endl;
 break;
 case 3:
 std::cout << "Wednesday" << std::endl;
 break;
}
// Output:
// Tuesday

char grade = 'B';

switch (grade) {
 case 'A':
 case 'B': // Intentional fall-through: A and B execute the same code
 case 'C':
 std::cout << "Passed!" << std::endl;
 break;
 case 'D':
 case 'F':
 std::cout << "Failed..." << std::endl;
 break;
}

condition ? expression1 : expression2

#include <iostream>

int main() {
 int a = 10, b = 20;
 
 int max = (a > b) ? a : b; // If a > b is true, max = a; otherwise max = b
 
 std::cout << "Maximum is: " << max << std::endl; // Output: Maximum is: 20
 
 return 0;
}

Maximum is: 20

#include <iostream>
#include <cstdlib> // For rand() and srand()
#include <ctime> // For time()

int main() {
 // Use current time as random seed (covered in detail later)
 std::srand(static_cast<unsigned int>(std::time(nullptr)));
 
 int secretNumber = std::rand() % 100 + 1; // Generate random number 1-100
 int guess;
 int attempts = 0;
 
 std::cout << "========== Number Guessing Game ==========\n";
 std::cout << "I'm thinking of a number from 1-100. Try to guess!\n\n";
 
 do {
 std::cout << "Please enter your guess: ";
 std::cin >> guess;
 attempts++;
 
 if (guess > secretNumber) {
 std::cout << "Too high!Try again。\n";
 } else if (guess < secretNumber) {
 std::cout << "Too low!Try again。\n";
 } else {
 std::cout << "\n🎉 Congratulations! You got it!\n";
 std::cout << "You guessed  " << attempts << " time。\n";
 }
 
 } while (guess != secretNumber);
 
 return 0;
}

========== Number Guessing Game ==========

I'm thinking of a number from 1-100. Try to guess!


Please enter your guess: 
Too high!Try again。

Too low!Try again。


🎉 Congratulations! You got it!

You guessed  times。

========== Number Guessing Game ==========
I'm thinking of a number from 1-100. Try to guess!

Please enter your guess: 50
Too high!Try again。
Please enter your guess: 25
Too low!Try again。
Please enter your guess: 37
Too high!Try again。
Please enter your guess: 31
🎉 Congratulations! You got it!
You guessed  4 time。

Please enter an integer: -5
-5 isNegative number

Please enter the first number: 10
Please enter an operator: /
Please enter the second number: 3
Result: 10 / 3 = 3.33333