Java Program: Sum of Primes

We think that 2 is the first prime, 3 is the second prime, 5 is the third prime, and so on.

Now, two integers n and m are given, 0<n<=m<=200. The program is to calculate the sum of n-th to m-th primes, including the n-th and the m-th prime.

Pay attention that it is to calculate the sum of n-th to m-th primes, but not the primes between n and m.

The program is following.

//Sum of Primes
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt(), m = in.nextInt(), count = 0, number = 2, sum = 0;
        while (count < m)
        {
            boolean IsPrime = true;
            for (int i=2;i<number;i++)
            {
                if (number%i==0)
                {
                    IsPrime = false;
                    break;
                }
            }
            if (IsPrime)
            {
                count++;
                if (count>=n)
                    sum += number;
            }
            number++;
        }
        System.out.println(sum);
    }
}

Java Program: Points In Three-dimensional Space

As is known to all, points in three-dimensional space can be expressed via space rectangular coordinates.There is a program, Point.java, in which I define a class named Point and do some simple operations on it.

//Point.java
public class Point
{
    int x, y, z; //3 coordinates of a point

    Point(int _x, int _y, int _z) //Constructor
    {
        x = _x;
        y = _y;
        z = _z;
    }

//To set the value of x, y and z coordinates
    void setx(int _x)
    {
        x = _x;
    }

    void sety(int _y)
    {
        y = _y;
    }

    void setz(int _z)
    {
        z = _z;
    }

//To calculate the square of distance between origin and the point
    int SquareOfDistance()
    {
        return x * x + y * y + z * z;
    }

//To test the program
    public static void main(String[] args)
    {
        Point point = new Point(3, 4, 5);

        System.out.println("The coordinate of this point is (" + point.x + "," + point.y + "," + point.z + "),and the square of distance between origin and the point is " + point.SquareOfDistance() + ".");
        point.setx(1);
        point.sety(2);
        point.setz(3);
        System.out.println("The coordinate of this new point is (" + point.x + "," + point.y + "," + point.z + "),and the square of distance between origin and the point is " + point.SquareOfDistance() + ".");
    }
}

The running results are following:

The coordinate of this point is (3,4,5),and the square of distance between origin and the point is 50.
The coordinate of this new point is (1,2,3),and the square of distance between origin and the point is 14.

Have you had a try?

What's Wrong With C4droid?

As an Android phone user,meanwhile a programming learner,I have got to seek for compilers which can be setup on my phone.I used C4droid to compile and run programs before,with its inside compiler TCC,GCC and G++,mainly to practice C language.However,some terrible things happened.
About the problem related to "int a[10];",which I mentioned in my blogs before,I consulted several people,but there was no exact conclusion.But I found that when I change the compiler TCC to GCC or G++,that problem disappeared.As expected, it's associated with the compiler.As to exact reason,I don't know.
What's worth,I run a C++ program by G++ successfully a few days ago,but it couldn't be run today.It's a simple program about conversion of one's height.

//Conversion Of Your Height
#include <iostream>
int main(void)
{
using namespace std;
int inchheight,foot,inch;
const int ConversionFactor=12;
cout<<"Input your height in inches(only integer allowed):__\b\b";
cin>>inchheight;
foot = inchheight / ConversionFactor;
inch = inchheight % ConversionFactor;
cout<<"You are "<<foot<<" feet(foot) "<<inch <<" inch(es) high."<<endl;
return 0;
}

Here I just display the errors shown on the screen.
What's wrong with C4droid?

Funny C Program:The Result Is Exactly The Same As Source Code!

Have you ever seen programs whose running results are absolutely the same as their source codes?Or do you think it is amazing for this phenomenon?Let's have a try.

//The Result Is Exactly The Same As Source Code

main(){char*a="main(){char*a=%c%s%c;printf(a,34,a,34);}";printf(a,34,a,34);}

Don't modify it,even adding a space,then run it.What surprise do you find?Is the result like the following?

Since finding this funny program,I try to explain it.

It seems this program is so simple,with too less code.You can say like this in a way,but in another way,do you understand this simple program?
In the main function,a character pointer,a,is defined,which points to the character string "main(){char*a=%c%s%c;printf(a,34,a,34);}".Then the statement "printf(a,34,a,34);" is run.Of course,two 'a' in the bracket point to the string.So this statement is equivalent to "printf("main(){char*a=%c%s%c;printf(a,34,a,34);}",34,"main(){char*a=%c%s%c;printf(a,34,a,34);}",34);".34 is the ASCII code of double quote,so the computer prints out the sentence:main(){char*a="main(){char*a=%c%s%c;printf(a,34,a,34);}";printf(a,34,a,34);},which is what you see on the screen,meanwhile the source code.
Is it funny?Have you learned something from this program?Enjoy it!