Java 实例 打印备用素数

在本教程中,我们将编写一个 Java 程序,以显示备用素数,直到给定值

Java 示例:打印备用素数

在以下示例中,我们有两个用户定义的方法:checkPrime()printAltPrime()

checkPrime()方法检查作为参数传递的数字是否为素数,如果数字为素数,则此方法返回 1,否则返回false

printAltPrime()方法打印备用素数,直到作为参数传递的值。

请阅读注释以了解程序的逻辑。

class JavaExample  
{ 

    //method for checking prime number
    static int checkPrime(int num) 
    { 
    int i, flag = 0; 
    for(i = 2; i<= num / 2; i++) 
    { 
       if(num % i == 0) 
       { 
           flag = 1; 
           break; 
       } 
    } 

    /* If flag value is 0 then the given number num
     * is a prime number else it is not a prime number
     */
    if(flag == 0) 
       return 1; 
    else
       return 0; 
    } 

    //Method for printing alternate prime numbers
    static void printAltPrime(int n) 
    { 
    /* When the temp value is odd then we are
     * not printing the prime number and when it is
     * even then we are printing it, this way we are
     * displaying alternate prime numbers
     */
    int temp = 2; 

    for(int num = 2; num <= n-1; num++) 
    { 
       //checking each number whether it is prime or not
       if (checkPrime(num) == 1) 
       {  
        // if temp is even then only print the prime number
        if (temp % 2 == 0) 
           System.out.print(num + " "); 

        temp ++; 
       } 
    } 
    } 

    public static void main(String[] args)  
    { 
    int num = 20; 
    System.out.print("Alternate prime numbers upto " + num+" are: ");  
    printAltPrime(num); 
    } 
}

输出:

Java 实例:打印备用素数

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Java 实例