Chapter 4 Drill // 4.1 + 4.2 + 4.3 + 4.4 - Principles & Practice Using C++

In all these exercises I am using Visual Studio Community 2015 and the header file "std_lib_facilities.h" which can be found here:


http://www.stroustrup.com/Programming/PPP2code/std_lib_facilities.h


My version is spelt differently so adjust the code accordingly if copying and pasting.

4.1 - Write a program that consists of a while-loop that (each time around the loop) reads in two ints and then prints them. Exit the program when a terminating '|' is entered.

#include "stdafx.h"
#include "std_lib_facilities_new_version.h"
using namespace std;



int main()
{
int one;
int two;

cout << "Please enter two integers: \n";


while (cin >> one >> two)
cout << one << '\n' << two << '\n' << "\nPlease enter two integers: \n";

keep_window_open();

return 0;
}

I'll be honest. At first this through me for a loop (pun intended), and searching the internet it seemed to throw other new users for loop because instead of actually just pressing '|' and hitting enter to close the program I thought he meant to create code that when '|' was entered the program would end....I know I'll wear my dunce hat. However I didn't actually know that '|' would terminate a program if pressed. Sometimes I wish Bjarne would make his instructions clearer.

4.2 - Change the program to write out 'the smaller value is: ' followed by the smaller of the numbers and 'the larger value is: ' followed by the larger value.


#include "stdafx.h"
#include "std_lib_facilities_new_version.h"
using namespace std;


int main()
{
int one;
int two;

cout << "Please enter two integers: \n";


while (cin >> one >> two)
{ 
{
if (one > two)
{
cout << "\nThe smaller value is: " << two << endl;
cout << "\nThe larger value is : " << one << endl;
}
else
{
cout << "\nThe smaller value is: " << one << endl;
cout << "\nThe larger value is : " << two << endl;
}

cout << "\nPlease enter two integers: \n";

}

}

keep_window_open();

return 0;

}

4.3 - Augment the program so that it writes the line 'the numbers are equal ' (only) if they are equal.

#include "stdafx.h"
#include "std_lib_facilities_new_version.h"
using namespace std;


int main()
{
int one;
int two;

cout << "Please enter two integers: \n";


while (cin >> one >> two)
{ 
{
if (one > two)
{
cout << "\nThe smaller value is: " << two << endl;
cout << "\nThe larger value is : " << one << endl;
}
else if (one < two)
{
cout << "\nThe smaller value is: " << one << endl;
cout << "\nThe larger value is : " << two << endl;
}
else
cout << "\nThe numbers are equal." << endl;

cout << "\nPlease enter two integers: \n";

}

}

keep_window_open();

return 0;

}

4.4 - Change the program so it uses doubles instead of ints.

I'm not going to bother showing code for this one because you simply just replace 'int' with 'double'. That's it.