2일차 추가

03_Operator

Ex01_plusplus

public class Ex01_plusplus {

	public static void main(String[] args) {
		// ++ : Postfix Increment Operator
		// -- : Postfix Increment Operator
		// 증감연산자 : ++, --
		// 사용형태 : ++변수명, 변수명++, --변수명, 변수명--
		// ++ : 값을 1 증가 시킴
		// -- : 값을 1 감소 시킴
		// ++num -> num = num + 1;
		int num = 100;
		System.out.println("num : " + num);
		num = num + 1;
		System.out.println("num = num + 1 : " + num);
		
		num = 100;
		System.out.println("num : " + num);
		++num;
		System.out.println("++num 실행후: " + num);
		
		num = 100;
		System.out.println("num : " + num);
		num++;
		System.out.println("num++ 실행후: " + num);
		
		//==========================
		System.out.println("=======================");
		int sum = 0;
		num = 100;
		System.out.println("num : " + num);
		System.out.println("sum : " + sum);
		
		sum = ++num + 1; //앞에 ++있으면 num값에 1이 증가 후 연산
		System.out.println("> sum = ++num + 1 연산후");
		System.out.println("num : " + num);
		System.out.println("sum : " + sum);
		System.out.println("-----------------------");
		
		sum = 0;
		num = 100;
		System.out.println("num : " + num);
		System.out.println("sum : " + sum);
		
		sum = num++ + 1; //뒤에 ++ 있으면 연산 후 1증가
		System.out.println("> sum = num++ + 1 연산후");
		System.out.println("num : " + num);
		System.out.println("sum : " + sum);
		
		System.out.println("=======================");
		sum = 0;
		num = 100;
		System.out.println("num : " + num);
		System.out.println("sum : " + sum);
		//sum = ++num + 1;
		++num; //num = num +1;
		sum = num + 1;
		System.out.println("> ++num; sum = num + 1 연산후");
		System.out.println("num : " + num);
		System.out.println("sum : " + sum);
		System.out.println("-----------------------");
		
	}

}

num : 100
num = num + 1 : 101
num : 100
++num 실행후: 101
num : 100
num++ 실행후: 101

num : 100
sum : 0

sum = ++num + 1 연산후
num : 101
sum : 102

num : 100
sum : 0

sum = num++ + 1 연산후
num : 101
sum : 101

num : 100
sum : 0

++num; sum = num + 1 연산후
num : 101
sum : 102

---

Ex02_gt_lt

public class Ex02_gt_lt {

	public static void main(String[] args) {
		// 비교연산자 : >, <, >= (크거나 같다), <= (작거나 같다)
		//			== (같다/동일하다), != (같지않다, 다르다)
		// 비교연산자의 결과 값 : true, false
		int num1 = 10;
		int num2 = 20;
		System.out.println(num1 > num2);
		System.out.println(num1 + ">" + num2 + (" : ") + (num1 > num2));
		System.out.println(num1 + "<" + num2 + (" : ") + (num1 < num2));
		System.out.println(num1 + ">=" + num2 + (" : ") + (num1 >= num2));
		System.out.println(num1 + "<=" + num2 + (" : ") + (num1 <= num2));
		System.out.println(num1 + "==" + num2 + (" : ") + (num1 == num2));
		System.out.println(num1 + "!=" + num2 + (" : ") + (num1 != num2));  //!는 not의 의미
		
	}

}

--- && (AND) ---
true && true : true
true && false : false
false && true : false
false && false : false

true && false : false

---

Ex03_AND_OR_NOT

public class Ex03_AND_OR_NOT {

	public static void main(String[] args) {
		// 논리연산자 : && (AND), || (OR), ! (NOT)
		// 논리연산자의 좌, 우에는 true, false 값이 있어야 한다
		int num1 = 10;
		int num2 = 20;
		boolean bool1 = true;
		boolean bool2 = false;
		
		System.out.println("--- && (AND) ---");
		System.out.println("true && true : " + (true && true)); 
		System.out.println("true && false : " + (true && false));
		System.out.println("false && true : " + (false && true));
		System.out.println("false && false : " + (false && false));
		
		System.out.println("----");
		System.out.println(bool1 + " && " + bool2 + " : " + (bool1 && bool2));
		
		System.out.println("----");
		// (num1 < num2) && bool1 : ??
		boolean result = (num1 < num2) && bool1;
		System.out.println(result);
		System.out.println(num1 + " < " + num2 + " && " + bool1 + " : " + result);
		
		
		System.out.println("----- || (OR) -----");
		System.out.println("true || true : " + (false || true)); //or는 좌우 하나만 true여도 true,
																  //좌우 모두 false일때만 false
		System.out.println("true || false : " + (true || false));
		System.out.println("false || true : " + (false || true));
		System.out.println("false || false : " + (false || false));
		result = num1 > num2 || bool2;
		System.out.println(num1 + " > " + num2 + " || " + bool2 + " : " + result);
		
		System.out.println("---- ! (NOT) ----");
		System.out.println(" !true " + !true); 
		System.out.println(" !false " + !false); 
		
		result = !(num1 > num2 || bool2);
		System.out.println("!(num1 > num2 || bool2) : " + result);
		
	}

}

--- && (AND) ---
true && true : true
true && false : false
false && true : false
false && false : false

true && false : false

true
10 < 20 && true : true
----- || (OR) -----
true || true : true
true || false : true
false || true : true
false || false : false
10 > 20 || false : false
---- ! (NOT) ----
!true false
!false true
!(num1 > num2 || bool2) : true

---

Ex04_plusEqual

public class Ex04_plusEqual {

	public static void main(String[] args) {
		// 대입연산자 : =, +=, -=, *=, /=, %=
		// 예) num = num + 2; ---> num += 2;
		int num1 = 10;
		int num2 = 20;
		int result = 0;
		
		System.out.println("result : " + result);
		result += 15; //result = result + 15; 동일하다
		System.out.println("result += 15 : " + result);
		
		result += 15;
		System.out.println("result += 15 : " + result);
		
		System.out.println("---- -= 연산 ----");
		result -= 10; // result = result - 10; 동일하다
		System.out.println("result -= 10 : " + result);
		System.out.println(); //빈줄 하나 추가
		
		result *= 10; //result = result * 10; 동일하다
		System.out.println("result *= 10 : " + result);
		
		result /= 130; //result = result / 130;
		System.out.println("result /= 130 : " + result);
		System.out.println(); //빈줄 하나 추가
		
		result = 10; //초기화
		System.out.println("result : " + result);
		result %= 3; //result = result % 3;
		System.out.println("result %= 3 : " + result);
	}

}

result : 0
result += 15 : 15
result += 15 : 30
---- -= 연산 ----
result -= 10 : 20

result *= 10 : 200
result /= 130 : 1

result : 10
result %= 3 : 1