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 TechnicalTalk » Programming and Web Development » C/C++
 Calculator Source Code

[Thomas]

Thomas  

 Calculator Source Code

I found this on dreamincode.net, maybe it will be useful to someone

Code:

#include <cstdlib>
#include <iostream>
 
using namespace std;
 
int main()
{
    double num;
    double num2;
    char choice;
    for (;;){
     do {
    cout<<"Welcome to thejoshcalculator. V1.5\n";
    cout<<"Please choose an option by entering the number, press q to quit\n";
    cout<<"1 - Addition\n";
    cout<<"2 - Subtraction\n";
    cout<<"3 - Division\n";
    cout<<"4 - Multiplication\n";
    cout<<"5 - Help\n";
    cout<<"6 - About This Program\n";
    cout<<"7 - Updates to this program\n";
    cin>>choice;
    } while ( choice < '1' || choice > '7' && choice != 'q');
    if (choice == 'q') break;
    switch (choice) {
           case '1':
                cout<<"Please enter a number\n";
                cin>>num;
                cout<<"Another number to be added\n";
                cin>>num2;
                cout<<num + num2;
                cout<<"\n";
                break;
           case '2':
                cout<<"Please enter a number\n";
                cin>>num;
                cout<<"Another number to be subtracted\n";
                cin>>num2;
                cout<<num - num2;
                cout<<"\n";
                break;
           case '3':
                cout<<"Please enter a number\n";
                cin>>num;
                cout<<"Another one to be divided\n";
                cin>>num2;
                cout<<num / num2;
                cout<<"\n";
                break;
           case '4':
                cout<<"Please enter a number\n";
                cin>>num;
                cout<<"Another one to be multiplied\n";
                cin>>num2;
                cout<<num * num2;
                cout<<"\n";
                break;
           case '5':
                cout<<"This is a simple calculator made by me - Josh.\n";
                cout<<"To select an option, type the number next to the option and press enter\n";
                cout<<"E.G. for division, you would type 3 and press enter.\n";
                cout<<"\n";
                break;
           case '6':
                cout<<"thejoshcalculator, made by Joshua Griggs - Copyright 2007. :)\n";
                cout<<"Feedback would be nice - joshieboy06@hotmail.com also, what programmes\n";
                cout<<"do people need. Please give me ideas for programs. Bye!!\n";
                cout<<"\n";
                break;
           case '7':
                cout<<"Updates include:  -double variable instead of int, so that decimals can be used.\n";
                cout<<"                  -do while loop so that you can exit the program yourself\n";
                cout<<"\n";
                break;
           default:
                    cout<<"That is not an option";
                   
                }
 
}
return 0;


}

[polas]

polas  

 Re: Calculator Source Code

There is quite a lot of code repetition there, which is bad style. This code could have been written much more succinctly. For instance, if you want the message to read "type a digit" instead of "Please enter a number" you would have to change the code in multiple places... of course not a major issue for something simple like this but in the real world this can cause a real headache.

[Thomas]

Thomas  

 Re: Calculator Source Code

Would you mind "fixing" it up so I can learn ways not to do things? This is C++

[polas]

polas  

 Re: Calculator Source Code

This is the way I would do it, I am not a C++ programmer so there may be better C++ ways. Also note how the origional author declares quite a few variables outside the scope they are required in... again I do not like this style particularly.

Code:

#include <cstdlib>
#include <iostream>
 
using namespace std;
 
int main()
{       
    while (true)
    {
    char choice;
     do {
    cout<<"Welcome to thejoshcalculator. V1.5\n";
    cout<<"Please choose an option by entering the number, press q to quit\n";
    cout<<"1 - Addition\n";
    cout<<"2 - Subtraction\n";
    cout<<"3 - Division\n";
    cout<<"4 - Multiplication\n";
    cout<<"5 - Help\n";
    cout<<"6 - About This Program\n";
    cout<<"7 - Updates to this program\n";   
    cin>>choice;
    } while ( choice < '1' || choice > '7' && choice != 'q');
    if (choice == 'q') break;
    if (choice == '1' || choice == '2' || choice=='3' || choice =='4')
    {
    double num;
    double num2;
    cout<<"Please enter a number\n";
        cin>>num;
        cout<<"Another number\n";
        cin>>num2;
        double theresult;
        if (choice=='1') theresult=num+num2;
        if (choice=='2') theresult=num-num2;
        if (choice=='3') theresult=num/num2;
        if (choice=='4') theresult=num*num2;
        cout<<theresult<<"\n";
    }
     if (choice=='5')
     {                 
                cout<<"This is a simple calculator made by me - Josh.\n";
                cout<<"To select an option, type the number next to the option and press enter\n";
                cout<<"E.G. for division, you would type 3 and press enter.\n\n";
}                       
}
return 0;
}

[Thomas]

Thomas  

 Re: Calculator Source Code

Ok so you basically just condensed the code, and removed unnnessacry things?

[polas]

polas  

 Re: Calculator Source Code

Reading code is like reading a page of English - it can look messy with poor style and obfusicated meaning, or it can be written well with few errors.

I did a couple of things:

1) Identified that options 1 - 4 are very similar (really only one line is different per option), so restructured them so that they could share the same code as much as possible, removing repetion and also cutting down the code size

2) Variables are declared in the scope that they are required rather than global to the function (cf. num, num2 and choice - see how their declarations are in a different place in my code)

3) I think while(true) is more readable than for (; - just my opinion, at the end of the day for is syntactic sugar for while anyway.

I did not bother to include all the option 6 and 7 crap - easy enough to add in. Could have cut the code down further by combining many of the couts onto one line (e.g. the menu), I would have taken his approach but it would make it slightly less clear for learning purposes.

Bear in mind, on average, 70% of effort spend creating software is in the maintenance phase. Whenever you write code, it really is essential that it is written clearly. I am currently working on porting and interfacing to, a 50000 line parallel simulation package written in C, thankfully for us it is written quite well and the code is clear(ish), but some of the less good coding styles adopted have caused real problems for us.

Nick

[Thomas]

Thomas  

 Re: Calculator Source Code

Thanks nick for helping, going to try and learn some more!

[polas]

polas  

 Re: Calculator Source Code

Np, some people argue that programming is an art rather than a skill - I dunno

[Thomas]

Thomas  

 Re: Calculator Source Code

I can see it being a art, and a skill too. That would be something that sticks in your head for a while...

[riya199002]

riya199002  

 Re: Calculator Source Code

Hey this is the calculator code of C language


#include <stdio. h>
#include <conio. h>
main()
{
  float n1,n2,s,d,p,q;
  clrscr();
  printf("\n Enter two nos");
  scanf("%f%f"&n1,&n2);
  s=n1+n2
  d=n1-n2;
  p=n1*n2;
  q=n1/n2;
  printf("\n Sum %f",s);
  printf("\n Difference %f",d);
  printf("\n Product %f",p);
  printf("\n Quotient %f",q);
  getch();
  return(0);
}

[Admin]

Admin  

 Re: Calculator Source Code

riya199002 thanks for posting the code.

Code is good for simple calculations.