Programming Forums > Application Development > C++

ViOLATiON · Sep 15th, 2005, 7:37 AM

Ok, I can make it do the actual operation itself, but I would like the user to be able to select which operation. Here is the source code I have written thus far, showing what would happen if someone chose multiplication:

(Toggle Plain Text)

#include <iostream>
using namespace std;
int main()
{
    string opchoice;
    int numberone;
    int numbertwo;
    int answer;
    cout<<"Choose your operation\n\nMultiplication = x\nSubtraction = -\nAddition = +\nDivision = /\n";
    cin>>opchoice;
    if ( opchoice == x ) {
    cout<<"Please input the first number you would like to multiply.\n\n";
    cin>>numberone;
    cin.get();
    cout<<"\n\nPlease input the second number you would like to multiply.\n\n";
    cin>>numbertwo;
    cin.get();
    answer = numberone * numbertwo;
    cout<<"\nThe final answer is "<<answer << "\n";
    cin.get();
    }
}

My problem is how do I make it so when someone types x and hits enter, that it does the operation. I'm assuming it has something to do with string x;

Please point me in the right direction

Thanks.

Polyphemus_ · Sep 15th, 2005, 8:03 AM

well... just put every operation in its own function, to make your code nice, and do something like:

(Toggle Plain Text)

string s;

getline(cin, s, '\n');
if (s == "Operation")
 do_something();
elseif (s == "Another Operation")
 do_something_else();

do you mean that?

ViOLATiON · Sep 15th, 2005, 8:26 AM

I changed opchoice to an integer, and put each number infront of the operation, and now it works.

(Toggle Plain Text)

// User: ViOLATiON
// Date: September 15th, 2005
// Comments: Basic Calculator
#include <iostream>
using namespace std;
int main()
{
    int opchoice;
    int numberone;
    int numbertwo;
    int answer;
    // Choose your operation
    cout<<"Choose your operation\n\n1 - Multiplication\n2 - Subtraction\n3 - Addition\n4 - Division\n\n"<<endl;
    cin>>opchoice;
    // Multiplication
    if (opchoice==1) 
    {
    cout<<"\nPlease input the first number you would like to multiply.\n\n";
    cin>>numberone;
    cin.get();
    cout<<"\n\nPlease input the second number you would like to multiply.\n\n";
    cin>>numbertwo;
    cin.get();
    answer = numberone * numbertwo;
    cout<<"\nThe final answer is "<<answer << "\n";
    cin.get();
    return 0;
    }
    // Subtraction
    if (opchoice==2)
    {
    cout<<"\nPlease input the first number you would like to subtract.\n\n";
    cin>>numberone;
    cin.get();
    cout<<"\n\nPlease input the second number you would like to subtract.\n\n";
    cin>>numbertwo;
    cin.get();
    answer = numberone - numbertwo;
    cout<<"\nThe final answer is "<<answer << "\n";
    cin.get();
    return 0;
    }
    // Addition
    if (opchoice==2)
    {
    cout<<"\nPlease input the first number you would like to add.\n\n";
    cin>>numberone;
    cin.get();
    cout<<"\n\nPlease input the second number you would like to add.\n\n";
    cin>>numbertwo;
    cin.get();
    answer = numberone + numbertwo;
    cout<<"\nThe final answer is "<<answer << "\n";
    cin.get();
    return 0;
    }
    // Division
    if (opchoice==2)
    {
    cout<<"\nPlease input the first number you would like to divide.\n\n";
    cin>>numberone;
    cin.get();
    cout<<"\n\nPlease input the second number you would like to divide.\n\n";
    cin>>numbertwo;
    cin.get();
    answer = numberone / numbertwo;
    cout<<"\nThe final answer is "<<answer << "\n";
    cin.get();
    return 0;
    }
}

DaWei · Sep 15th, 2005, 8:35 AM

I am going to suggest a stretching exercise for you. One can gather the user input and process it properly whether it's one, two, three, or more items. For a typical (non-polish) calculator one gathers operators and operands and performs the operation when one perceives a 'go' condition. The use of a stack or two is often the approach. If you want to delve into that and have problems with it, there's help on the forum aplenty.

InfoGeek · Sep 15th, 2005, 8:44 AM

Same Output. Code reduced by 1/2

(Toggle Plain Text)

// User: ViOLATiON
// Date: September 15th, 2005
// Comments: Basic Calculator
#include <iostream>
using namespace std;
int main()
{
    int opchoice;
    int numberone;
    int numbertwo;
    int answer;
    // Choose your operation
    cout<<"Choose your operation\n\n1 - Multiplication\n2 - Subtraction\n3 - Addition\n4 - Division\n\n"<<endl;
    cin>>opchoice;
	
	cout<<"\nPlease input the first number\n\n";
    cin>>numberone;
    cin.get();
    cout<<"\n\nPlease input the second number\n\n";
    cin>>numbertwo;
	cin.get();

	switch(opchoice)
	{
	case 1: 
		// Multiplication
       answer = numberone * numbertwo;
	   break;
	case 2:
	   // Subtraction

		answer = numberone - numbertwo;
		break;
    // Addition
    case 3:
		answer = numberone + numbertwo;
		break;    
	case 4:
		//division
		answer = numberone / numbertwo;

	}
    cout<<"\nThe final answer is "<<answer << "\n";
    cin.get();
    return 0;
    
}

ViOLATiON · Sep 15th, 2005, 8:48 AM

Holy :eek:

DaWei · Sep 15th, 2005, 10:18 AM

I know I sound like a broken record to you guys, but this is germane to being a good programmer. Check your functions for success. I broke this program with my first keystroke. See the attached image (quality reduced because of compression).

ViOLATiON · Sep 15th, 2005, 10:26 AM

Hmm.. I'll give it a shot before asking for help

ViOLATiON · Sep 15th, 2005, 10:37 AM

I'm confused what does it mean by "The variable 'answer' is being used without being defined"

Isn't it defined by the operation, ie: answer = numberone * numbertwo;

or is it defined at the int answer; line

DaWei · Sep 15th, 2005, 10:51 AM

No, it is not defined there. Your input failed and zooped right past that code because nothing qualified. Let me make some points. You are not going to have personal access to all your users for training purposes, or to tell them that they are ignorant SOBs. Let your code detect untrained or inattentive or malicious users. Let you code tell them that they are ignorant SOBs.

Let me say again that a good function, whether written by you, or someone else, does not promise to deliver the goods. It promises to deliver or tell its user that it failed to do so. If you don't ask it which of those conditions obtains, how will you know?

Let me stress again that some code, when it fails, can damage or kill someone. That may sound far-fetched; it is not. In a case like that one accrues criminal liability, even if it's just due to carelessness.

Coding is part due consideration and part habit. The longer you code, the larger the habit part gets. It's best not to build bad habits. If you decide to present code as an example, and want to keep it short, you may decide OVERTLY to leave out some important things. If you do, it might be wise to say so. Otherwise, any knowledgeable reader is entitled to judge the author to be a schlocky programmer.

If you read the documentation regarding iostreams, you will see how to make sure things went properly. If you want example code, post back.

Sep 15th, 2005, 7:37 AM	#1
ViOLATiON Programmer Join Date: Sep 2005 Posts: 58 Rep Power: 4	Console Calc Ok, I can make it do the actual operation itself, but I would like the user to be able to select which operation. Here is the source code I have written thus far, showing what would happen if someone chose multiplication: (Toggle Plain Text) #include <iostream> using namespace std; int main() { string opchoice; int numberone; int numbertwo; int answer; cout<<"Choose your operation\n\nMultiplication = x\nSubtraction = -\nAddition = +\nDivision = /\n"; cin>>opchoice; if ( opchoice == x ) { cout<<"Please input the first number you would like to multiply.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to multiply.\n\n"; cin>>numbertwo; cin.get(); answer = numberone * numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); } } #include <iostream> using namespace std; int main() { string opchoice; int numberone; int numbertwo; int answer; cout<<"Choose your operation\n\nMultiplication = x\nSubtraction = -\nAddition = +\nDivision = /\n"; cin>>opchoice; if ( opchoice == x ) { cout<<"Please input the first number you would like to multiply.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to multiply.\n\n"; cin>>numbertwo; cin.get(); answer = numberone * numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); } } My problem is how do I make it so when someone types x and hits enter, that it does the operation. I'm assuming it has something to do with string x; Please point me in the right direction Thanks.

Sep 15th, 2005, 8:03 AM	#2
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	well... just put every operation in its own function, to make your code nice, and do something like: (Toggle Plain Text) string s; getline(cin, s, '\n'); if (s == "Operation") do_something(); elseif (s == "Another Operation") do_something_else(); string s; getline(cin, s, '\n'); if (s == "Operation") do_something(); elseif (s == "Another Operation") do_something_else(); do you mean that?

Sep 15th, 2005, 8:26 AM	#3
ViOLATiON Programmer Join Date: Sep 2005 Posts: 58 Rep Power: 4	I changed opchoice to an integer, and put each number infront of the operation, and now it works. (Toggle Plain Text) // User: ViOLATiON // Date: September 15th, 2005 // Comments: Basic Calculator #include <iostream> using namespace std; int main() { int opchoice; int numberone; int numbertwo; int answer; // Choose your operation cout<<"Choose your operation\n\n1 - Multiplication\n2 - Subtraction\n3 - Addition\n4 - Division\n\n"<<endl; cin>>opchoice; // Multiplication if (opchoice==1) { cout<<"\nPlease input the first number you would like to multiply.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to multiply.\n\n"; cin>>numbertwo; cin.get(); answer = numberone * numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } // Subtraction if (opchoice==2) { cout<<"\nPlease input the first number you would like to subtract.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to subtract.\n\n"; cin>>numbertwo; cin.get(); answer = numberone - numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } // Addition if (opchoice==2) { cout<<"\nPlease input the first number you would like to add.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to add.\n\n"; cin>>numbertwo; cin.get(); answer = numberone + numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } // Division if (opchoice==2) { cout<<"\nPlease input the first number you would like to divide.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to divide.\n\n"; cin>>numbertwo; cin.get(); answer = numberone / numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } } // User: ViOLATiON // Date: September 15th, 2005 // Comments: Basic Calculator #include <iostream> using namespace std; int main() { int opchoice; int numberone; int numbertwo; int answer; // Choose your operation cout<<"Choose your operation\n\n1 - Multiplication\n2 - Subtraction\n3 - Addition\n4 - Division\n\n"<<endl; cin>>opchoice; // Multiplication if (opchoice==1) { cout<<"\nPlease input the first number you would like to multiply.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to multiply.\n\n"; cin>>numbertwo; cin.get(); answer = numberone * numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } // Subtraction if (opchoice==2) { cout<<"\nPlease input the first number you would like to subtract.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to subtract.\n\n"; cin>>numbertwo; cin.get(); answer = numberone - numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } // Addition if (opchoice==2) { cout<<"\nPlease input the first number you would like to add.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to add.\n\n"; cin>>numbertwo; cin.get(); answer = numberone + numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } // Division if (opchoice==2) { cout<<"\nPlease input the first number you would like to divide.\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number you would like to divide.\n\n"; cin>>numbertwo; cin.get(); answer = numberone / numbertwo; cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } }

Sep 15th, 2005, 8:35 AM	#4
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	I am going to suggest a stretching exercise for you. One can gather the user input and process it properly whether it's one, two, three, or more items. For a typical (non-polish) calculator one gathers operators and operands and performs the operation when one perceives a 'go' condition. The use of a stack or two is often the approach. If you want to delve into that and have problems with it, there's help on the forum aplenty. __________________ 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

Sep 15th, 2005, 8:44 AM	#5
InfoGeek Professional Programmer Join Date: Jun 2005 Location: India, The great. Posts: 435 Rep Power: 4	Same Output. Code reduced by 1/2 (Toggle Plain Text) // User: ViOLATiON // Date: September 15th, 2005 // Comments: Basic Calculator #include <iostream> using namespace std; int main() { int opchoice; int numberone; int numbertwo; int answer; // Choose your operation cout<<"Choose your operation\n\n1 - Multiplication\n2 - Subtraction\n3 - Addition\n4 - Division\n\n"<<endl; cin>>opchoice; cout<<"\nPlease input the first number\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number\n\n"; cin>>numbertwo; cin.get(); switch(opchoice) { case 1: // Multiplication answer = numberone * numbertwo; break; case 2: // Subtraction answer = numberone - numbertwo; break; // Addition case 3: answer = numberone + numbertwo; break; case 4: //division answer = numberone / numbertwo; } cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } // User: ViOLATiON // Date: September 15th, 2005 // Comments: Basic Calculator #include <iostream> using namespace std; int main() { int opchoice; int numberone; int numbertwo; int answer; // Choose your operation cout<<"Choose your operation\n\n1 - Multiplication\n2 - Subtraction\n3 - Addition\n4 - Division\n\n"<<endl; cin>>opchoice; cout<<"\nPlease input the first number\n\n"; cin>>numberone; cin.get(); cout<<"\n\nPlease input the second number\n\n"; cin>>numbertwo; cin.get(); switch(opchoice) { case 1: // Multiplication answer = numberone * numbertwo; break; case 2: // Subtraction answer = numberone - numbertwo; break; // Addition case 3: answer = numberone + numbertwo; break; case 4: //division answer = numberone / numbertwo; } cout<<"\nThe final answer is "<<answer << "\n"; cin.get(); return 0; } __________________ PFO - My daily dose of technology.

Sep 15th, 2005, 8:48 AM	#6
ViOLATiON Programmer Join Date: Sep 2005 Posts: 58 Rep Power: 4	Holy :eek:

Sep 15th, 2005, 10:26 AM	#8
ViOLATiON Programmer Join Date: Sep 2005 Posts: 58 Rep Power: 4	Hmm.. I'll give it a shot before asking for help

Sep 15th, 2005, 10:37 AM	#9
ViOLATiON Programmer Join Date: Sep 2005 Posts: 58 Rep Power: 4	I'm confused what does it mean by "The variable 'answer' is being used without being defined" Isn't it defined by the operation, ie: answer = numberone * numbertwo; or is it defined at the int answer; line

Sep 15th, 2005, 10:51 AM	#10
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	No, it is not defined there. Your input failed and zooped right past that code because nothing qualified. Let me make some points. You are not going to have personal access to all your users for training purposes, or to tell them that they are ignorant SOBs. Let your code detect untrained or inattentive or malicious users. Let you code tell them that they are ignorant SOBs. Let me say again that a good function, whether written by you, or someone else, does not promise to deliver the goods. It promises to deliver or tell its user that it failed to do so. If you don't ask it which of those conditions obtains, how will you know? Let me stress again that some code, when it fails, can damage or kill someone. That may sound far-fetched; it is not. In a case like that one accrues criminal liability, even if it's just due to carelessness. Coding is part due consideration and part habit. The longer you code, the larger the habit part gets. It's best not to build bad habits. If you decide to present code as an example, and want to keep it short, you may decide OVERTLY to leave out some important things. If you do, it might be wise to say so. Otherwise, any knowledgeable reader is entitled to judge the author to be a schlocky programmer. If you read the documentation regarding iostreams, you will see how to make sure things went properly. If you want example code, post back. __________________ 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

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Programming Forums > Application Development > C++

Console Calc