프로그래밍 실습 #1

Byung-Hyun Ha

bhha@pusan.ac.kr

정수를 사용한 연산 : 섭씨를 화씨로import java.util.Scanner;

public class Temp {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

System.out.print("Temp. in degree Celsius? ");int c = s.nextInt();

int f = c * 9 / 5 + 32;

System.out.println("It's " + f + " deg. F.");}

}

실수를 사용한 연산 : 섭씨를 화씨로import java.util.Scanner;

public class Temp {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

System.out.print("Temp. in degree Celsius? ");double c = s.nextDouble();

double f = c * 9 / 5 + 32;

System.out.println("It's " + f + " deg. F.");}

}

실수에 관하여import java.util.Scanner;

public class Big {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

System.out.print("Input number? ");double n = s.nextDouble();

for (int i = 0; i < 10000; i++) {n = n + 0.0001;

}

System.out.println("Result: " + n);}

}

실수에 관하여 1 을 입력해보자

어떤 결과 vs. 실제 결과

10000000000 을 입력해보자 ( 동그라미가 10 개 )

1000000000000000 을 입력해보자 ( 동그라미가 15 개 )

33221 2

1

2

1

2

10001.0 bbb

)2(0122

33 110122213 aaaa

문자열import java.util.Scanner;

public class Name {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

System.out.print("Name? ");String name = s.nextLine();

int n = name.indexOf(' ');String sir = name.substring(0, n);String given = name.substring(n + 1, name.length());

System.out.print("Sir name is " + sir +" and given name is " + given);

}}

Java 2 Platform API Specification

반올림 : 잘못된 프로그램import java.util.Scanner;

public class Round {

public static void main(String[] args) { Scanner s = new Scanner(System.in);

System.out.print("Input number? "); double n = s.nextDouble();

double r = (int)(n + 0.5);

System.out.println(n + " is rounded off to " + r); }}

반올림import java.util.Scanner;

public class Round {

public static void main(String[] args) { Scanner s = new Scanner(System.in);

System.out.print("Input number? "); double n = s.nextDouble();

double r = Math.floor(n + 0.5);

System.out.println(n + " is rounded off to " + r); }}

약수 1

import java.util.Scanner;

public class Divisor {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

System.out.print("Input number? ");int n = s.nextInt();

for (int i = 1; i <= n; i++) {if ((n % i) == 0) {

System.out.print(i + " ");}

}}

}

약수 2

import java.util.Scanner;

public class Divisor {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

System.out.print("Input number? ");int n = s.nextInt();

for (int i = 1; i <= n; i++) {if ((n / i * i) == n) {

System.out.print(i + " ");}

}}

}

소수 (Prime Number)

import java.util.Scanner;

public class Prime {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

System.out.print("Input number? ");int n = s.nextInt();

boolean isPrime = true;for (int i = 2; i < n; i++) {

if (n / i * i == n) {isPrime = false;break;

}}

if (isPrime) {System.out.println("Prime Number");

} else {System.out.println("Not Prime Number");

}}

}

숫자 피라미드 출력

Input number (less than 10)? 6 0 010 01210 0123210 012343210 012345432100123456543210

숫자 피라미드 출력import java.util.Scanner;

public class Pramid {

public static void main(String[] args) {Scanner s = new Scanner(System.in);System.out.print("Input number (less than 10)? ");int n = s.nextInt();

for (int i = 0; i <= n; i++) {for (int j = 0; j < n - i; j++) {

System.out.print(' ');}

for (int j = 0; j <= i; j++) {System.out.print(j);

}

for (int j = i - 1; j >= 0; j--) {System.out.print(j);

}

System.out.println();}

}}

숫자 n 개 입력 (999 를 입력하면 끝 )

import java.util.Scanner;

public class InputN {

public static void main(String[] args) {Scanner s = new Scanner(System.in);

int[] ns = new int[1000];int count = 0;

for (int i = 0; i < 1000; i++) {System.out.print((i + 1) + "'th: ");ns[i] = s.nextInt();

if (ns[i] == 999) {count = i;break;

}}

System.out.print("Your input: ");for (int i = 0; i < count; i++) {

System.out.print(ns[i] + " ");}

}}

정렬public class Sort {

public static void main(String[] args) {int[] ns = {4, 5, 1, 7, 1, 3};

for (int i = 0; i < ns.length - 1; i++) {for (int j = i + 1; j < ns.length; j++) {

if (ns[i] > ns[j]) { int temp = ns[i]; ns[i] = ns[j]; ns[j] = temp;}

}}

System.out.println("Result: ");for (int i = 0; i < ns.length; i++) {

System.out.print(ns[i] + " ");}

}}

빈도수 구하기public class Frequency {

public static void main(String[] args) {int[] ns = {4, 5, 1, 7, 1, 3, 1, 3, 1, 4};int[] frequency = new int[20];

for (int i = 0; i < 20; i++) {frequency[i] = 0;

}

for (int i = 0; i < ns.length; i++) {frequency[ns[i]]++;

}

for (int i = 0; i < 20; i++) {System.out.println(i + ": " + frequency[i]);

}}

}