Help with troubleshooting code.

[GeeStuR]

What's wrong with the codes I have written?


In my assignment I am given a test code.

#include<iostream>
#include<cassert>
#include"Number.h"

using namespace std;

int main(int argc, char * argv[])

{
    Number nine(9);
    assert(!nine.isPrime());
    assert( nine.isDivisibleBy(1));
    assert(!nine.isDivisibleBy(2));
    assert( nine.isDivisibleBy(3));
    assert(!nine.isDivisibleBy(8));
    assert( nine.isDivisibleBy(9));

    Number seven(7);
    assert( seven.isPrime());
    assert( seven.isDivisibleBy(1));
    assert(!seven.isDivisibleBy(2));
    assert(!seven.isDivisibleBy(3));
    assert( seven.isDivisibleBy(7));

    NumberseventySeven(77);
    assert(!seventySeven.isPrime());

    Number seventyThree(73);
    assert(seventyThree.isPrime());

    Number twentySeven(27);
    assert(!twentySeven.isPrime());
    assert(!twentySeven.isDivisibleBy(2));
    assert(twentySeven.isDivisibleBy(3));
    assert(twentySeven.isDivisibleBy(9));

    cout << "All tests passed.\n";

}

I have to develop a class called "Number" that represents an integer value. The class should have a constructor that takes the integer value as its only argument. The constructor should store this value in a private member variable. Here is what I am able to come up with so far.

class Number
{
   private:
    int val;

   public:
    Number(int);
    bool isPrime();
    bool isDivisibleBy(int);
};

What do I have to add to the class code?


The second part of my question is that I have to define a public member function called "isPrime" that takes no argument and returns a bool. If the number is a prime number, then isPrime returns true, otherwise it returns false.


I also have to define another member function called isDivisibleBy that takes a single integer argument and returns a bool. If the integer is passed into "isDivisibleBy" is a divisor for the number, then the function returns true, otherwise it returns false. Here's what I came up with

#include "Number.cpp"
#include <cmath>
 
Number::Number(int a){
    val = a;
    }
 
bool Number::isPrime(){
    int a = this->val;
    if(a==1)
     return false;

    if(a==2)
     return true;

    int sq = sqrt(a);
    
    for(int i=2;i<sq;i++){
      if(a%i==0)
     return false;
}
    return true;
}
 
bool Number::isDivisibleBy(int d){
   if(this->val % d == 0)
   return true;
   return false;
}

When I test the codes I get that " assert( seven.isPrime()); " failed. What did I do wrong? Thanks.

[MiiNiPaa]

That strange, seven.isPrime() assert should not fail, however !nine.isPrime() should.

[MikeyBoy]

nine.isPrime() should fail, because 9 is not a prime.

!nine.isPrime() should not fail, because 9 is not a prime.

[MiiNiPaa]

@MikeBoy

Correction:

!nine.isPrime() should fail if will be called in his code.

Assertion failed!

Program: E:\Users\MiiNiPaa\home\Developement\CodeBlocks\projects\Test\bin\Debug\Test.exe
File: E:\Users\MiiNiPaa\home\Developement\CodeBlocks\projects\Test\main.cpp, Line 51

Expression: !nine.isPrime()

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.

Process returned 3 (0x3)   execution time : 2.928 s
Press any key to continue. 

How to fix: Change condition in third snippet, line 18 from < to <=