Programming Forums > Application Development > C++

ferret · Dec 7th, 2005, 4:10 PM

This program executes halfway and then terminates:
#include <iostream>
using namespace std;

int main()
{
int a, b;

cout << "Enter first number: ";
cin >> a;
cout << "Enter second number: ";
cin >> b;

if(a < b) {
cout << "First number is less than second.\n";
cout << "Their difference is: " << b-a;

}

return 0;
}
It asks me for the first number and then the second number and when I'm done typing them in I get no console output. The program just terminates. Do you know what I'm doing wrong? I know int a has to be less then int b. It just doesnt work and it should.

DaWei · Dec 7th, 2005, 4:22 PM

You'd like some advice, and we'd like to give it. The first piece is: Read the rules/FAQ for a new community when you visit. Use code tags around your code.

Now, to your problem. You're probably just missing the output because the program fires up, runs, presents the output, and disappears before you see it. This has been covered in the forums twice in the last week alone. Exercise some search/research skills that will stand you in good stead later.

It is also possible that you or your user are breaking the stream so that the program is just zooping straight through to the end. This too is a frequent problem with novices that have failed to cover the documentation for the functions they use.

It is also possible that the test isn't being met and that the program is operating correctly in skipping those statements.

I suggest a search of recent threads using terms like "pause", "cls", "disappear", "getchar", "get". Sure, you're bound to get some junk. On the other hand, junk is relative.

nnxion · Dec 7th, 2005, 6:41 PM

Assuming you're using windows, put:

(Toggle Plain Text)

system("pause");

before you return 0.

zirener · Dec 8th, 2005, 10:22 AM

Or, you could do something like this, which probably is more portable:

(Toggle Plain Text)

#include <limits>
//...
cin.ignore(std::numeric_limits<int>::max(), '\n');
cin.get();
//...

UnKnown X · Dec 8th, 2005, 10:31 AM

Quote:

Originally Posted by zirener

Or, you could do something like this, which probably is more portable:

(Toggle Plain Text)

#include <limits>
//...
cin.ignore(std::numeric_limits<int>::max(), '\n');
cin.get();
//...

I suggest putting cin.sync() before the long cin.ignore(). That way you'll be almost sure it'll work.

HaCkeR · Dec 8th, 2005, 10:39 AM

well for starter your IF function only covers a < b so if b < a then it runs the program correctly and ends.

secondly your program runs fine but you need include a WAIT statement or cin.get() so the the program doesnt end immediatly.
here is an example of cin.get() with the if statement complete

(Toggle Plain Text)

#include <iostream>
using namespace std;
 int main()
{
int a, b;
cout << "Enter first number: ";
cin >> a;
cout << "Enter second number: ";
cin >> b;
if(a < b) {
	 cout << "First number is less than second.\n";
	 cout << "Their difference is: " << b-a;
	 cin.get(); // user presses a button to end
	 }
	 
	 else {
		  cout << "First number is bigger than second.\n";
		  cout << "Thier difference is: " << a - b;
		  cin.get(); // user presses a button to end
		  }
cin.get(); // user presses a button to end
return 0;
}

UnKnown X · Dec 8th, 2005, 11:03 AM

That indentation is horrible, IMO.

Here's what I suggest. I also added an else if for whenever a == b.

(Toggle Plain Text)

#include <iostream>
using namespace std;

int main()
{
    int a, b;
    cout << "Enter first number: ";
    cin >> a;
    cout << "Enter second number: ";
    cin >> b;
    if(a < b)
    {
        cout << "First number is less than second.\n";
        cout << "Their difference is: " << b-a << endl;
        cin.sync();
        cin.get(); // user presses a button to end
    }
    else if (a == b)
    {
        cout << "The numbers are equal.\n";
        cout << "Their difference is: 0\n";
        cin.sync();
        cin.get();
    }
    else
    {
        cout << "First number is greater than second.\n";
        cout << "Their difference is: " << a - b << endl;
        cin.sync();
        cin.get(); // user presses a button to end
    }

    cin.sync();
    cin.get(); // user presses a button to end
    return 0;
}

HaCkeR · Dec 8th, 2005, 12:48 PM

Dunno why my indentation is like that it realy is horrible isnt it

The Dark · Dec 8th, 2005, 5:47 PM

Quote:

Originally Posted by HaCkeR

Dunno why my indentation is like that it realy is horrible isnt it

It is probably tab characters in your original source not being handled properly in the web form.

Edit: Just tried it from my editor and it worked, so it is not the web form.

Dec 7th, 2005, 4:10 PM	#1
ferret Newbie Join Date: Dec 2005 Posts: 10 Rep Power: 0	Newbie Help This program executes halfway and then terminates: #include <iostream> using namespace std; int main() { int a, b; cout << "Enter first number: "; cin >> a; cout << "Enter second number: "; cin >> b; if(a < b) { cout << "First number is less than second.\n"; cout << "Their difference is: " << b-a; } return 0; } It asks me for the first number and then the second number and when I'm done typing them in I get no console output. The program just terminates. Do you know what I'm doing wrong? I know int a has to be less then int b. It just doesnt work and it should. __________________ eat, drink and be merry for tomorrow we die.

Dec 7th, 2005, 4:22 PM	#2
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	You'd like some advice, and we'd like to give it. The first piece is: Read the rules/FAQ for a new community when you visit. Use code tags around your code. Now, to your problem. You're probably just missing the output because the program fires up, runs, presents the output, and disappears before you see it. This has been covered in the forums twice in the last week alone. Exercise some search/research skills that will stand you in good stead later. It is also possible that you or your user are breaking the stream so that the program is just zooping straight through to the end. This too is a frequent problem with novices that have failed to cover the documentation for the functions they use. It is also possible that the test isn't being met and that the program is operating correctly in skipping those statements. I suggest a search of recent threads using terms like "pause", "cls", "disappear", "getchar", "get". Sure, you're bound to get some junk. On the other hand, junk is relative. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Dec 7th, 2005, 6:41 PM	#3
nnxion Programming Guru Join Date: Jun 2005 Location: elemental plane Posts: 1,429 Rep Power: 5	Assuming you're using windows, put: (Toggle Plain Text) system("pause"); system("pause"); before you return 0. __________________ "Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for." -- Socrates

Dec 8th, 2005, 10:22 AM	#4
zirener Newbie Join Date: Dec 2005 Location: Space, Tellus, Europe, Norway, Oslo Posts: 23 Rep Power: 0	Or, you could do something like this, which probably is more portable: (Toggle Plain Text) #include <limits> //... cin.ignore(std::numeric_limits<int>::max(), '\n'); cin.get(); //... #include <limits> //... cin.ignore(std::numeric_limits<int>::max(), '\n'); cin.get(); //...

Dec 8th, 2005, 10:39 AM	#6
HaCkeR Hobbyist Programmer Join Date: Nov 2005 Location: UK Posts: 131 Rep Power: 0	well for starter your IF function only covers a < b so if b < a then it runs the program correctly and ends. secondly your program runs fine but you need include a WAIT statement or cin.get() so the the program doesnt end immediatly. here is an example of cin.get() with the if statement complete (Toggle Plain Text) #include <iostream> using namespace std; int main() { int a, b; cout << "Enter first number: "; cin >> a; cout << "Enter second number: "; cin >> b; if(a < b) { cout << "First number is less than second.\n"; cout << "Their difference is: " << b-a; cin.get(); // user presses a button to end } else { cout << "First number is bigger than second.\n"; cout << "Thier difference is: " << a - b; cin.get(); // user presses a button to end } cin.get(); // user presses a button to end return 0; } #include <iostream> using namespace std; int main() { int a, b; cout << "Enter first number: "; cin >> a; cout << "Enter second number: "; cin >> b; if(a < b) { cout << "First number is less than second.\n"; cout << "Their difference is: " << b-a; cin.get(); // user presses a button to end } else { cout << "First number is bigger than second.\n"; cout << "Thier difference is: " << a - b; cin.get(); // user presses a button to end } cin.get(); // user presses a button to end return 0; }

Dec 8th, 2005, 11:03 AM	#7
UnKnown X Hobbyist Programmer Join Date: Dec 2005 Location: Sandvika, Norway Posts: 114 Rep Power: 0	That indentation is horrible, IMO. Here's what I suggest. I also added an else if for whenever a == b. (Toggle Plain Text) #include <iostream> using namespace std; int main() { int a, b; cout << "Enter first number: "; cin >> a; cout << "Enter second number: "; cin >> b; if(a < b) { cout << "First number is less than second.\n"; cout << "Their difference is: " << b-a << endl; cin.sync(); cin.get(); // user presses a button to end } else if (a == b) { cout << "The numbers are equal.\n"; cout << "Their difference is: 0\n"; cin.sync(); cin.get(); } else { cout << "First number is greater than second.\n"; cout << "Their difference is: " << a - b << endl; cin.sync(); cin.get(); // user presses a button to end } cin.sync(); cin.get(); // user presses a button to end return 0; } #include <iostream> using namespace std; int main() { int a, b; cout << "Enter first number: "; cin >> a; cout << "Enter second number: "; cin >> b; if(a < b) { cout << "First number is less than second.\n"; cout << "Their difference is: " << b-a << endl; cin.sync(); cin.get(); // user presses a button to end } else if (a == b) { cout << "The numbers are equal.\n"; cout << "Their difference is: 0\n"; cin.sync(); cin.get(); } else { cout << "First number is greater than second.\n"; cout << "Their difference is: " << a - b << endl; cin.sync(); cin.get(); // user presses a button to end } cin.sync(); cin.get(); // user presses a button to end return 0; }

Dec 8th, 2005, 12:48 PM	#8
HaCkeR Hobbyist Programmer Join Date: Nov 2005 Location: UK Posts: 131 Rep Power: 0	Dunno why my indentation is like that it realy is horrible isnt it

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