Question

Please have a look at the following java code

import java.util.Scanner;

public class Main
{
    static int mul=1;
    static String  convert;
    static  char[] convertChar ;
    static StringBuffer buffer = new StringBuffer("");

    public static void main(String[]args)
    {

        Scanner scan = new Scanner(System.in);

        int number=0;
        int loopValue = scan.nextInt();
       //System.out.println("print: "+loopValue);

        for(int i=0;i<loopValue;i++)
        {
            number = scan.nextInt();
           // System.out.println("print: "+number);

            for(int a=1;a<=number/2;a++)
            {
                if(number%a==0)
                {
                    //System.out.println(a);
                    mul = mul*a;
                    //System.out.println(mul);
                }
            }

           convert  = String.valueOf(mul);
           convertChar = convert.toCharArray();

           if(convertChar.length>4)
            {
               /*System.out.print(convertChar[convertChar.length-4]);
               System.out.print(convertChar[convertChar.length-3]);
               System.out.print(convertChar[convertChar.length-2]);
               System.out.print(convertChar[convertChar.length-1]);
               System.out.println();*/

               buffer.append(convertChar[convertChar.length-4]);
               buffer.append(convertChar[convertChar.length-3]);
               buffer.append(convertChar[convertChar.length-2]);
               buffer.append(convertChar[convertChar.length-1]);

                System.out.println(buffer);

            }
            else
            {
                System.out.println(mul);
            }

            //System.out.println(mul);
            mul = 1;
        }

    }
}

This code is built to compute the product of positive divisors of a given number. I have used scanner here because I don’t know how many inputs will be entered. That is why I can’t go something like

int a, b;

cin >> a >> b

in C++. All the inputs will be inserted by a test engine, into one single like like following

6 2 4 7 8 90 3456

How can I implement the Java “Scanner” using C++ ? Is there a header file for that? Please help!

Answer 1

You seem to be using Scanner to read one integer at a time from the standard input stream. This is easily accomplished with the extraction operator, operator>>.

Replace this code:

    Scanner scan = new Scanner(System.in);

    int number=0;
    int loopValue = scan.nextInt();
   //System.out.println("print: "+loopValue);

    for(int i=0;i<loopValue;i++)
    {
        number = scan.nextInt();
       // System.out.println("print: "+number);

With this:

    int number=0;
    int loopvalue=0;
    std::cin >> loopvalue;

    for(int i = 0; i < loopValue; i++)
    {
        std::cin >> number;

You should check the value of std::cin after the >> operations to ensure that they succeeded.

Refs:

• http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Scanner.html
• http://en.cppreference.com/w/cpp/io/basic_istream/operator_gtgt