반복문 <-- while문

끝이 알수 없는것

1.반복횟수를 안상태에서 반복 하는것 <- for

2.반복횟수를 모른 상태에서 반복 하는것 <- while

 

 

import java.util.Scanner;

public class while문 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			System.out.print("정수 입력 : ");
			int a = sc.nextInt();
			if(a>10) {
				
				break;
			}
		}
		System.out.println("종료되었습니다.");
	}

}

 

 

방식1

import java.util.Random;
import java.util.Scanner;

public class while문2 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Random random = new Random();
		int a = random.nextInt(19)+1;
		while(true) {
			System.out.print("number : ");
			int b = sc.nextInt();
			if(b<a) {
				System.out.println("up");
			}else if(b>a) {
				System.out.println("down");
			}else {
				System.out.println("success");
				break;
			}
			
		}
		
	}

}

방식2

 

import java.util.Random;
import java.util.Scanner;

public class while문2 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Random random = new Random();
		int a = random.nextInt(19)+1;
		int c=0;
		while(true) {
			System.out.print("number : ");
			int b = sc.nextInt();
			c++;
			if(b<a) {
				System.out.println("up");
			}else if(b>a) {
				System.out.println("down");
			}else {
				System.out.println("success");
				System.out.println(c+"번째만에 완성");
				break;
			}
			
			if(c==5) {
				System.out.println("Fail...");
				break;
			} 
			
		}
		
	}

}

import java.util.Scanner;

public class while문3 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		while(true) {
			System.out.print("아이디를 입력하세요 : ");
			String a = sc.next();
			System.out.print("비번을 입력하세요 : ");
			String b = sc.next();
			if(a.equals(b)) {
				System.out.println("로그인 성공");
				System.out.println(a+"님 환영합니다.");
				break;
			}
				System.out.println("로그인 실패");
		}
		
	}

}

 

import java.util.Scanner;

public class while문4 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.print("현재 몸무게 : ");
		int a = sc.nextInt();
		System.out.print("목표 몸무게 : ");
		int b = sc.nextInt();
		
		int num=0;
		int num1=0;
		
		while(true) {
			num++;
			System.out.print(num+"주차 감량 몸무게 : ");
			int c = sc.nextInt();
			num1+=c;
			
			if(a-num1<b) {
				System.out.println(a-num1+"kg 달성!! 축하합니다!");
				break;
			}
		}
		
		System.out.println("종료되었습니다.");
	}

}

2번

 

import java.util.Scanner;

public class while문4심화 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		// 심화 : 목표 몸무게가 현재 몸무게 보다 크다면 반복하기
		System.out.print("현재 몸무게 : ");
		int a = sc.nextInt();
		System.out.print("목표 몸무게 : ");
		int b = sc.nextInt();

		while (a < b) {
			System.out.println("다시 입력해주세요");
			System.out.print("목표 몸무게 : ");
			b = sc.nextInt();
		}
		int n=0;
		while(a>b) {
			n++;
			System.out.println(n+"주차 감량 몸무게");
			int minus = sc.nextInt();
			a-=minus;
		}
		System.out.println(a+"몸무게 달성을 축하합니다.");
	}
}

 

 

 

import java.util.Random;
import java.util.Scanner;

public class while문5 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		Random random = new Random();
		int num = 0;

		while (true) {
			int a = random.nextInt(9) + 1;
			int b = random.nextInt(9) + 1;
			System.out.print(a + "+" + b + "=");
			int c = sc.nextInt();
			if ((a + b) != c) {
				num++;
				System.out.println("Fail...");
			} else {
				System.out.println("Success");
			}
			if (num == 3) {
				System.out.println("Game Over!");
				break;
			}
		}

	}

}

2번