Question

Q1. Write a C++ class called Time24h that describes a time of the day in hours, minutes, and seconds. It should contain the following methods: • Three overloaded constructors (one of which must include a seconds value). Each constructor should test that the values passed to the constructor are valid; otherwise, it should set the time to be midnight. A display() method to display the time in the format hh:mm:ss. (Note: the time can be displayed as 17:4:34, i.e. leading zeros are not required). Q2. Add the following methods to your class of Q1: • A method that returns the time as the total (closest) number of minutes since midnight. • A int compare(Time24h t) method that accepts a single Time24h object and returns -1,0 or 1, according to whether the time object on which the method is being called is less than, equal to or greater than the time object "t" passed as the method parameter. Q3. Implement the same class as in Q1+2, except in Java. Test that it works. Q4. Write a C++ class called DataArray which internally stores an array of double values and the length of the array, as private variables. The class should have a constructor DataArraylint size) which creates the array using new. given the specified array size. It should also have a constructor DataArray(double all, int size) which creates the array and initialises it using the array passed into the constructor. The class should also have a destructor which frees previously allocated memory, using deletell Q5. Add the following public methods to your DataArray class of 04: double min(), which returns the minimum value in the DataArray, • double maxl), which returns the maximum value in the DataArray and a method DataArray scaleBy(double factor), which returns a new DataArray object containing the data scaled by the given factor. Q6. Write a simple C++ class of your choosing which has a constructor and a destructor, which each print a message to indicate that they have been called. Using your class, write a function that takes an object of your class, passed by value. Write a similar function that takes an object of your class, passed by reference. Pass an object of your class to each function and explain the difference you see in the constructor/destructor messages.

Answer 1

ANSWER1

#include <bits/stdc++.h>

using namespace std;

class Time24h
{
private:
int hh,mm,ss;
public:
Time24h()
{
hh=mm=ss=0;
}
Time24h(int num)
{
hh=mm=0;
ss=num;
if(!(ss>=0 && ss<=59))
ss=0;
}
Time24h(int num1,int num2,int num3)
{
hh=num1;
mm=num2;
ss=num3;
if(!(hh>=0 && hh<=23)||!(mm>=0 && mm<=59)||!(ss>=0 && ss<=59))
{
hh=mm=ss=0;
}
}
void display()
{
if(hh>=0 && hh<=9)
cout<<"0"<<hh;
else
cout<<hh;
cout<<":";
if(mm>=0 && mm<=99)
cout<<"0"<<mm;
else
cout<<mm;
cout<<":";
if(ss>=0 && ss<=9)
cout<<"0"<<ss;
else
cout<<ss;
cout<<endl;
}
};
int main()
{
Time24h obj1(21,4,4);
obj1.display();
return 0;
}

output:
21:04:04

ANSWER 2

#include <bits/stdc++.h>

using namespace std;

class Time24h
{
private:
int hh,mm,ss;
public:
Time24h()
{
hh=mm=ss=0;
}
Time24h(int num)
{
hh=mm=0;
ss=num;
if(!(ss>=0 && ss<=59))
ss=0;
}
Time24h(int num1,int num2,int num3)
{
hh=num1;
mm=num2;
ss=num3;
if(!(hh>=0 && hh<=23)||!(mm>=0 && mm<=59)||!(ss>=0 && ss<=59))
{
hh=mm=ss=0;
}
}
void display()
{
if(hh>=0 && hh<=9)
cout<<"0"<<hh;
else
cout<<hh;
cout<<":";
if(mm>=0 && mm<=99)
cout<<"0"<<mm;
else
cout<<mm;
cout<<":";
if(ss>=0 && ss<=9)
cout<<"0"<<ss;
else
cout<<ss;
cout<<endl;
}
int totalclosest()
{
int num=hh*60 + mm;
return num;
}
int compare(Time24h t)
{
if(hh>t.hh)
return 1;
else if(hh == t.hh)
{
if(mm >t.mm)
return 1;
else if(mm == t.mm)
{
if(ss > t.ss)
return 1;
else if(ss == t.ss)
return 0;
}
}
return -1;
}
};
int main()
{
Time24h obj1(21,4,4);
cout<<"The current Time is : ";
obj1.display();
int close=obj1.totalclosest();
cout<<"The number of minutes passed since midnight : "<<close<<endl;
Time24h t(21,8,8);
int res=obj1.compare(t);
if(res==1)
cout<<"obj1 has greater time than t ";
else if(res==0)
cout<<"obj1 has equal time with t ";
else
cout<<"obj1 has smaller time with t ";
cout<<endl;
return 0;
}

output:

The current Time is : 21:04:04
The number of minutes passed since midnight : 1264
obj1 has smaller time with t

ANSWER 4

#include <bits/stdc++.h>

using namespace std;

class DataArray
{
private:
int len;
double *arr=new double;
public:
DataArray(int num)
{
len=num;
for(int i=0;i<num;i++)
arr[i] = 0;
}
DataArray(double *res,int num)
{
len=num;
for(int i=0;i<num;i++)
arr[i]=res[i];
}
void display()
{
cout<<"The array : ";
for(int i=0;i<len;i++)
cout<<arr[i]<<" ";
cout<<endl;
}
~DataArray()
{
len=0;
delete[] arr;
}

};
int main()
{
DataArray obj1(5);
obj1.display();
double *res=new double;
for(int i=0;i<7;i++)
res[i]=i+1;
DataArray obj2(res,7);
obj2.display();
return 0;
}

output:
The array : 0 0 0 0 0
The array : 1 2 3 4 5 6 7

ANSWER 5

#include <bits/stdc++.h>

using namespace std;

class DataArray
{
private:
int len;
double *arr=new double;
public:
DataArray(int num)
{
len=num;
for(int i=0;i<num;i++)
arr[i] = 0;
}
DataArray(double *res,int num)
{
len=num;
for(int i=0;i<num;i++)
arr[i]=res[i];
}
void display()
{
cout<<"The array : ";
for(int i=0;i<len;i++)
cout<<arr[i]<<" ";
cout<<endl;
}
double min()
{
double minn = INT_MAX;
for(int i=0;i<len;i++)
{
if(arr[i]<minn)
minn=arr[i];
}
return minn;
}
double max()
{
double maxx = INT_MIN;
for(int i=0;i<len;i++)
{
if(arr[i]>maxx)
maxx=arr[i];
}
return maxx;
}
DataArray scaleby(double factor)
{
DataArray obj(arr,len);
for(int i=0;i<obj.len;i++)
obj.arr[i] = arr[i]*factor;
return obj;
}
~DataArray()
{
len=0;
delete[] arr;
}

};
int main()
{
DataArray obj1(5);
obj1.display();
double *res=new double;
for(int i=0;i<7;i++)
res[i]=i+1;
DataArray obj2(res,7);
obj2.display();
cout<<obj2.max()<<" is the maximum element in the array "<<endl;
cout<<obj2.min()<<" is the minimum element in the array "<<endl;
DataArray obj3 = obj2.scaleby(2);
obj3.display();
return 0;
}

output:

The array : 0 0 0 0 0
The array : 1 2 3 4 5 6 7
7 is the maximum element in the array
1 is the minimum element in the array
The array : 2 4 6 8 10 12 14

ANSWER 6

#include <bits/stdc++.h>

using namespace std;

class DataArray
{
public:
int num=0;
DataArray()
{
cout<<"Constructor is called "<<endl;
}
~DataArray()
{
cout<<"Destructor is called "<<endl;
}
};
void callbyvalue(DataArray obj)
{
obj.num = 10;
}
void callbyreferene(DataArray &obj)
{
obj.num = 10;
}

int main()
{
DataArray obj;
cout<<"Initial value of obj.num : "<<obj.num<<endl;
callbyvalue(obj);
cout<<"After calling callbyback function , value of obj.num : "<<obj.num<<endl;
callbyreferene(obj);
cout<<"After calling callbyreference function , value of obj.num : "<<obj.num<<endl;
return 0;
}

/*
output:
Constructor is called
Initial value of obj.num : 0
Destructor is called
After calling callbyback function , value of obj.num : 0
After calling callbyreference function , value of obj.num : 10
Destructor is called

*/

/*
callbyvalue - The call by value method of passing arguments to a function copies the actual value of an argument into the formal parameter of the function. ... In general, it means the code within a function cannot alter the arguments used to call the function.

callbyreference - The call by reference method of passing arguments to a function copies the address of an argument into the formal parameter. Inside the function, the address is used to access the actual argument used in the call. It means the changes made to the parameter affect the passed argument.

Constructor - it is called when the object is first created.It invoked automatically.
Desetructor - it is called whent the object goes out of scope. It also invoked automatically.
*/