我需要一個程序來打印任意兩個間隔之間的所有素數，然后打印兩個間隔之間有多少個素數。所以我有一個正在運行的代碼，但它不會打印數字 2 并且我知道 2 是一個素數。它正在正確地執行其他所有操作。我嘗試了一些其他可以打印 2 的代碼，但如果我輸入負數，它也會給出負數。import java.util.Scanner;class Main { public static void main(String args[]) { int first, last, flag = 0, i, j; Scanner scanner = new Scanner(System.in); System.out.print("\nEnter the lower bound : "); first = scanner.nextInt(); System.out.print("\nEnter the upper bound : "); last = scanner.nextInt(); System.out.println("The prime numbers in between the entered limits are :"); int x = 0; for (i = first; i <= last; i++) { for (j = 2; j < i; j++) { if (i % j == 0) { flag = 0; break; } else { flag = 1; } } if (flag == 1) { x++; System.out.println(i + " "); } } System.out.println("Total number of prime numbers between " + first + " and " + last + " are " + x); }}因此，如果我輸入 -5（上限）和 10（下限），它應該打?。?2 3 5 7 -5 到 10 之間的素數總數是 4但它打印 3 5 7 -5 到 10 之間的素數總數是 3
4 回答
婷婷同學_
TA貢獻1844條經驗 獲得超8個贊
只需在循環之前添加以下幾行for，它就會給出預期的輸出：
int x = 0;
if (first<3) {
System.out.println(2);
x++;
}
您的更新程序將是：
import java.util.Scanner;
class Main {
public static void main(String args[]) {
int first, last, flag = 0, i, j;
Scanner scanner = new Scanner(System.in);
System.out.print("\nEnter the lower bound : ");
first = scanner.nextInt();
System.out.print("\nEnter the upper bound : ");
last = scanner.nextInt();
System.out.println("The prime numbers in between the entered limits are :");
int x = 0;
if (first<3) {
System.out.println(2);
x++;
}
for (i = first; i <= last; i++) {
for (j = 2; j < i; j++) {
if (i % j == 0) {
flag = 0;
break;
} else {
flag = 1;
}
}
if (flag == 1) {
x++;
System.out.println(i + " ");
}
}
System.out.println("Total number of prime numbers between " + first + " and " + last + " are " + x);
}
}
慕村225694
TA貢獻1880條經驗 獲得超4個贊
您可以檢查此代碼（經過優化，因為它在大范圍內運行得更快。在迭代所有數字之前循環返回）
public static void main(String args[]) {
int first;
int last;
Scanner scanner = new Scanner(System.in);
System.out.print("\nEnter the lower bound : ");
first = scanner.nextInt();
System.out.print("\nEnter the upper bound : ");
last = scanner.nextInt();
System.out.println("The prime numbers in between the entered limits are :");
int x = 0;
for (int i = first; i <= last; i++) {
if (isPrime(i)) {
x++;
System.out.println(i + " ");
}
}
System.out.println("Total number of prime numbers between " + first + " and " + last + " are " + x);
}
static boolean isPrime(int n)
{
if (n <= 1) //less than 2 are not
return false;
if (n <=3) // 2 and 3 are prime
return true;
if (n % 2 == 0 || n % 3 == 0)
return false;
for (int i = 5; i * i <= n; i = i + 6)
if (n % i == 0 || n % (i + 2) == 0)
return false;
return true;
}
你不需要旗幟。
繁花如伊
TA貢獻2012條經驗 獲得超12個贊
嘗試這個：
import java.util.Scanner;
public class Main {
public static void main(String args[]) {
int i, n;
int num;
int maxCheck;
boolean isPrime = true;
String primeNumbersFound = "";
Scanner sc=new Scanner(System.in);
System.out.println("Enter the first number: ");
num = sc.nextInt();
System.out.println("Enter the second number: ");
maxCheck= sc.nextInt();
for (i = num; i <= maxCheck; i++) {
isPrime = CheckPrime(i);
if (isPrime) {
primeNumbersFound = primeNumbersFound + i + " ";
}
}
System.out.println("Prime numbers from " + num + " to " + maxCheck + " are:");
System.out.println(primeNumbersFound);
}
public static boolean CheckPrime(int n) {
int remainder;
for (int i = 2; i <= n / 2; i++) {
remainder = n % i;
if (remainder == 0) {
return false;
}
}
return true;
}
}
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