simple check.

this was the only coding exercise that I've had trouble with so far on this great learning adventure :)

just looking to see if there was a better way to do this, or if any tips could be thrown my way. the program runs well.
cheers

Code:

---

#include <iostream>
#include <string>
using namespace std;


int main (){
  int answer;
  int obama = 0;
  int romney = 0;
  int option3 = 0;
    while (obama < 5 && romney < 5 && option3 < 5)
    {
      cout<< " who would you like to see become president?\n";
      cout<< "1. obama\n2. romney\n3. The bank owns the government.\n";
      cin>> answer;
     
      if (answer == 1){
          obama++;
          }
             
      else if (answer == 2){
          romney++;
          }
                                 
      else if (answer == 3){
          option3++;
          }
          else {
                cout<< "please enter a number 1-3\n";
                }                 
      }   
      cout<< "obama- " << obama << "\n";
      cout<< "romney- " << romney << "\n";
      cout<< "doesn't matter- " << option3 << endl;
                   
                           
     
 
 
                      cin.ignore ();
                      cin.get ();
                     
}

---

I suggest giving the user the message "please enter a number 1-3\n" from the beginning.I can not understand the purpose of lines 41,42.You get the user to input something without a reason.
A non programming tip would be i think,why all the inputs have the same value?I mean somebody may wants very much to select one president,that you may give the ability to the user to input a weight to his input.

I assumed choosing 1-3 was obvious, i only put the "please choose between 1-3" in as a default message to anything BUT 1-3.
I'm still early in learning and lines 40+41 are the only way I know of (for now) to keep the program open for me to see the results if any option gets to 5.
also it is meant to be a "poll" exercise, so that user(s) cast a vote, it is stored, and when there is a "winner" (first to hit 5) it will be displayed. imgaine 17 people in a circle passing my laptop around, entering 1-3. (VERY unpractical but again this was just an exercise to practice loops, Boolean, and If statements

Ok i see.It is too obvious ,i agree.But your programs in general have to be easy to use to everyone!Even though people who are not familiar with pc'es.Imagine an old man who does not know anything about computers.I believe that a programmer ought to help the user inputs something acceptable.
Another think i would change,is that at the end of the program you could print who the winner is and not all the results,or both(the results and the winner ;) )
As for lines 40-41 when you start writing at an IDE(e.g. netbeans) you should not need them.

very true, I'll make it a habit of being specific, as i can see it could cause problems down the road.. printing the winner would make more sense ;)
thanks mate

I also suggest you think in terms of extensibility. For each option you have supported, you have copied similar code, added a new variable, and a string corresponding to that variable.

Can you think of a way of structuring your code so, if you want to add or remove options (say, if Obama decides not to run again for the presidency, or some other politician does) you can do it with minimal changes, rather than having to duplicate multiple bits of code (as you are)?

That may sound like gilding the lily, but I can probably do the same thing as you with half the lines of code, and STILL be able to evolve it more easily than you can.

I'm trying.. really hard.. to think of another way....... but i can't. I don't think I know enough fundamentally to re-structure this into a more efficient code :/ are you speaking of my if statements when referring to duplicating? from my current perspective I cannot see how I would be able to compact this, I just finished learning loops (still trying to grasp efficient use of them) the other day, and I'm currently trying to learn about functions outside of main. Its hard for me to fully understand because the examples are so... simple..
This was an example given for me.. Surely I understand its meant to be simple for learning purposes.. but I won't understand it if I don't see a viable use for it.

Code:

---


#include <iostream>
using namespace std;

int multiply (int x, int y);

int main ()
{
    int x;
    int y;
    cout<< "please enter two numbers to be multiplied.\n";
    cin>> x, y;
    cin.ignore();
    cout<< "the product of your two numbers is " << int multiply (x, y) << "\n" //why wouldn't i just enter x * y..
    cin.get();
//do i need a return 0; here?
}

int multiply (int x, int y);
{
    return x * y;
}

---

Quote:

---

As for lines 40-41 when you start writing at an IDE(e.g. netbeans) you should not need them.

---

Yes you will - The ide console runner may provide the halt on the window disappearing after execution- but using the build debug or release version would not - unless the programmer provides it.

Quote:

---

Its hard for me to fully understand because the examples are so... simple..

---

I hear you, but the idea is that you need to extrapolate from the simple examples and see how it maps to your own code and requirements - you can't expect to find an exact match for your programming goal every time you do a search, so if you hit related tutorials etc then you will get good at taking what you need from them- in terms of learning and concept.

Quote:

---

//do i need a return 0; here?

---

Yes! that is the standard - Elysia has posted some good links on this if i recall, maybe she will drop one in this thread for you.

Quote:

---

int multiply (x, y) << "\n" //why wouldn't i just enter x * y..

---

absolutley, you could if you wanted - obviously other things would have to change to accomodate this - your function defintion as it stands needs two arguments - x , y - If you just passed in a*b then that would only be one argument, ie a single value.

And ignoring functions, if what you meant was "couldn't i just put x*y in the cout statement?" then yes - that is valid also.

Maybe for practice, rewrite it using the function with your x*y idea, remebering the function defintion itself, and it's return staement will change.. by the way -get rid of the 'int' part, you dont need to declare the return type when you call the function - you have already declared it at the top of your file in the prototype; function calls only require their name and args.

i spotted a mistake while rewriting the code, line 11 should have been written cin>> x >> y; ugh caused like 15 mins worth of frustration over two arrows.. is this the life of a programmer!? ;) lol anyways, if i replaced the multiply function with x * y (one arguement, right?) then wouldn't the program still work, since I'm simply not using 'multiply' at all ?
Im slowly getting the hang of this.. thanks guys.

Code:

---

#include <iostream>


using namespace std;


int multiply (int x, int y);


int main ()
{
 int x;
 int y;   
    cout<< "enter two numbers to multiply\n";
    cin>> x >> y;
    cin.ignore();
    cout<< "product of two numbers is " << x * y << "\n"; //if i DID call the function here, it would only be << multiply (x, y) << correct?
    cin.get();
    return 0;
}


int multiply (int x, int y)
{
    return x * y;
}

---

//

Code:

---

#include <iostream>

using namespace std;

int multiply(int multipliedValue)
{
    return multipliedValue;
}

int main()
{
    int val = 5;

    cout << val * val << "\n";

    cout << multiply(val * val);

    return 0;
}
//

---

so essentially, its the same thing, functions are just to organize code a little better? I suppose if I were to use x*y (or another, more complicated equation) very often it would make sense to put it into a function that i could just call multiple times.. thanks alot mate, as of yesterday I was utterly lost on the subject of functions, now I've got a solid grasp on them.. next up, Switch Case!! expect another NOOBY post by me soon ;)
cheers

You need to look at more code - Its much more regular to place variables in the function call - rather than maths - sometimes its handy to do like in recursion where you can alter the value of the variable passed in with -- or ++ or whatever.
Check out the 'How do i...' pages of the faq's they are really very useful - i remember i printed off all the stuff i was interested in in a booklet form, quick lookup then when needed.

Quote:

---

Originally Posted by Mike Beal

I'm trying.. really hard.. to think of another way....... but i can't.

---

Alright, I'll take pity.

This is your code from your first post

Code:

---

#include <iostream>
#include <string>
using namespace std;
 
 
int main (){
  int answer;
  int obama = 0;
  int romney = 0;
  int option3 = 0;
    while (obama < 5 && romney < 5 && option3 < 5)
    {
      cout<< " who would you like to see become president?\n";
      cout<< "1. obama\n2. romney\n3. The bank owns the government.\n";
      cin>> answer;
     
      if (answer == 1){
          obama++;
          }
             
      else if (answer == 2){
          romney++;
          }
                                   
      else if (answer == 3){
          option3++;
          }
          else {
                cout<< "please enter a number 1-3\n";
                }                 
      } 
      cout<< "obama- " << obama << "\n";
      cout<< "romney- " << romney << "\n";
      cout<< "doesn't matter- " << option3 << endl;
                   
                           
     
   
   
                      cin.ignore ();
                      cin.get ();
                     
}

---

Now, compare it with my version. What does it do that your code does not (other than some minor changes of what the program outputs, and that I've removed the cin.get()/cin.ignore() closing)? How easy it it to extend?

Code:

---

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main ()
{
  vector<string> label;
  label.push_back("obama");    // Add strings to label to enable options
  label.push_back("romney");
  label.push_back("doesn't matter");

  size_t i, size = label.size();
  vector<int> result(size, 0);

  while (*max_element(result.begin(), result.end()) < 5)
  {
        cout<< "Who would you like to see become president?\n";

        for (i = 0; i < size; ++i) cout<< (i + 1) << ". " << label[i] << '\n';

        size_t answer;
        cin >> answer;

        if (answer <= 0 || answer > size)
            cout<< "Invalid input.  Please enter a value in the range 1-" << size << '\n';
        else
            ++result[answer-1];
  }

  for (i = 0; i < size; ++i) cout<< label[i] << "- " << result[i] << '\n';
}

---

Now, okay, I've used a few things from the standard library you probably don't know about yet. But this could be adapted to not use the standard library (other than for output to cout). Instead of a vector of strings, for example, it is possible to use an array of char *.

I haven't even gone out of my way to optimise this code. For example, I have not eliminated unnecessary variables, and have not bothered to break the code up into separate functions, which could make the code even simpler.

I would also personally remove the "using namespace std;" directive (and use std::cout rather than cout) but that's a discussion for another day.

Quote:

---

I would also personally remove the "using namespace std;" directive (and use std::cout rather than cout) but that's a discussion for another day.

---

i am intrigued - without wanting to divert this thread would like to hear your thinking on that.

Quote:

---

Originally Posted by rogster001

i am intrigued - without wanting to divert this thread would like to hear your thinking on that.

---

Using namespace directives potentially cause ambiguity. For example, if there is a name in the global (unnamed) namespace that is the same as a name within namespace std, then any usage of that name will always be ambiguous after a "using namespace std" directive.

Once that ambiguity occurs, there are only two possible options to resolve it, since the effect of a "using namespace" directive can't be undone by any means except removing the directive.

The first approach to resolving such an ambiguity is to fully qualifying all names (i.e. prefixing all names with their namespace). That negates the point of the existing "using namespace" directive for all names where ambiguity has been introduced.

The second approach is to remove the "using namespace" directive, which then makes it necessary to ensure all names (except, optionally, those in the global namespace) are fully qualified.

Practically, for anything except the tiniest code samples, I find the effort of resolving such an ambiguity upon encountering it exceeds the effort of avoiding it in the first place (i.e. not employing any "using namespace" directives, and fully qualifying all names except - optionally - those that are local to a file or in the global namespace).

And since I generally write code with a view to maintaining it, using it in a larger system, or extending it ...... I find it better to simply avoid "using namespace" directives in real code. The only time I employ a "using namespace" directive is actually in code samples I post in forums.

I'm not fussed if people choose to employ a "using namespace" directive in their own code. They wear the impact. But a "using namespace" directive in a header file is a no-no, since it forces me to manage impacts whether I wish to or not. If I encounter a "using namespace" directive in a header file for a library, I do not use that library. Period.

Quote:

---

Originally Posted by rogster001

Yes! that is the standard - Elysia has posted some good links on this if i recall, maybe she will drop one in this thread for you.

---

Actually, no.
The C++ standard says that main will implicitly return 0 if you don't add it yourself, so there is no need.
Whether it is good or practice omitting it is discussable, and I'm sure there are people on both sides.

I prefer just saying "using std::cout; using std::cin;" o3o

Quote:

---

Originally Posted by Elysia

Actually, no.
The C++ standard says that main will implicitly return 0 if you don't add it yourself, so there is no need.
Whether it is good or practice omitting it is discussable, and I'm sure there are people on both sides.

---

I had no idea about that. I usually scramble to make sure main returns something. Thank you O:

Quote:

---

Now, compare it with my version. What does it do that your code does not (other than some minor changes of what the program outputs, and that I've removed the cin.get()/cin.ignore() closing)? How easy it it to extend?

---

firstly, thank you very much grumpy for taking the time to do this.. now to answer your question, it seems to me that your code allows me to enter new candidates/options without adding other sections of else if statements. also I wouldn't have to go back and change the condition under which the loop ends, and if i did add new candidates the option to choose them would be of no work, seeing as adding a candidate also makes it an option.

i truly appreciate your help, but just to put it out there, I am very early on in learning.. Therefore I don't know of the terms vector or label.. and I will have to study this code for some time to fully understand each step. (there is alot going on that I am very unfamiliar with) However It DOES show me a more compact way of doing this and that's a start, even if I don't fully get it... YET :)

I will look into those FAQs Rogster, thanks much!

Quote:

---

Originally Posted by Mike Beal

i truly appreciate your help, but just to put it out there, I am very early on in learning.. Therefore I don't know of the terms vector or label.. and I will have to study this code for some time to fully understand each step. (there is alot going on that I am very unfamiliar with) However It DOES show me a more compact way of doing this and that's a start, even if I don't fully get it... YET :)

---

Fair enough. I accept you're on the learning curve.

vector and string, as I used them in the last sample, are names of type in the C++ standard library, and you'll find them eventually discussed in any decent textbook or reference material on C++. When you learn about templates (an important part of the C++ language, but there are plenty of things to learn before you can learn properly) you'll better understand what the syntax vector<string> means. For now, just look at "vector<string> label;" as declaring a variable named label that is a vector of strings. "label" is just an arbitrary variable name. A vector is a logical construct that contains a group of multiple elements.

Quote:

---

Actually, no.
The C++ standard says that main will implicitly return 0 if you don't add it yourself, so there is no need.
Whether it is good or practice omitting it is discussable, and I'm sure there are people on both sides.

---

Yes I saw that i ahd got mixed up with the int main() / void main() thing - but i still didnt know about any implicit return value so nice one.

one way i can think of to reduce all the if statements are

Code:

---

#include<conio.h>
#include<iostream.h>
 int main()
 {
        int obama=0,romney=0,bank=0,answer=0;
        while(obama<5&&romney<5&&bank<5)
        {
                cout<<endl<<"who do you want to see as president?";
                cout<<endl<<"1.obama\n"<<"2.romney\n"<<"3.bank..";
                cin>>answer;
                switch(answer)
                {
                        case 1:obama++;
                                        break;
                        case 2:romney++;
                                        break;
                        case 3:bank++;
                                        break;
                        default:cout<<endl<<"what the??";
               
                }       
        }
        cout<<endl<<"obama->"<<obama<<endl<<"romney->"<<romney<<endl<<"bank->"<<bank;
        getch();
 }

---

the braces can be avoided:biggrin:lthis way
do give your feedback
cin.ignore() can be replaced by getch().


just keep this in mind when you move forward and become a high performance server programmer one day...:)a series of nested if statements is faster than a switch statement. Compared to if, a switch statement is only faster if there are 100 or more conditions.

Quote:

---

Originally Posted by theju112

cin.ignore() can be replaced by getch()

---

getch() is non-standard, as is <conio.h>. Furthermore, the correct header is <iostream>, not <iostream.h>

Quote:

---

Originally Posted by theju112

just keep this in mind when you move forward and become a high performance server programmer one day...:)a series of nested if statements is faster than a switch statement. Compared to if, a switch statement is only faster if there are 100 or more conditions.

---

Spoken like a true noob. Are you a troll or are you really that clueless?

Okay, let me put it clearly...
Anyone giving advice that ridiculous is not qualified to make ANY performance recommendations whatsoever! Kapish?!