Cola Machine #1

Question

I have been working on the code listed here.
I am working on Problem #2, 0 stars. Here's what I have to do:

Write a program that presents the user w/ a choice of your 5 favorite beverages (Coke, Water, Sprite, ... , Whatever). Then allow the user to choose a beverage by entering a number 1-5. Output which beverage they chose.

NOTE: I won't be creating a switch statement or making a error message if you give a value other than one that is 1-5, because that are part of the next step in the project.

using std::cout;
using std::cin;
using std::endl;


int main()
{
    int UserSodaChoice;

    cout << "Cola Machine V1" << endl;
    cout << "1. Coca-Cola" << endl;
    cout << "2. Sprite" << endl;
    cout << "3. Fanta" << endl;
    cout << "4. Mountain Dew" << endl;
    cout << "5. Pepsi" << endl;
    cout << "Pick your favorite beverage: ";
    cin >> UserSodaChoice;

    if (UserSodaChoice == 1)
    {
        cout << "I don't like Coca-Cola...";
    }
    if (UserSodaChoice == 2)
    {
        cout << "Sprite is ok I guess.";
    }
    if (UserSodaChoice == 3)
    {
        cout << "Waayyyy too much sugar.";
    }
    if (UserSodaChoice == 4)
    {
        cout << "Mountain Dew! Nice.";
    }
    if (UserSodaChoice == 5)
    {
        cout << "Eww. People don't drink Pepsi these days, it ain't the 90's.";
    }
    cout << "\n\n\n\t\t\t";
}

Answer 1

Good for you, avoiding using namespace std;.

Within the constraints you requested (i.e. no switch block, no error handling), there's not that much to review.

Avoid excessive use of endl, as that flushes the output unnecessarily. You could write the menu as one long constant. (String literals placed immediately after each other will be treated as one.) Flush it just once at the end, using std::flush. As @LokiAstari points out, you don't need to explicitly flush at all; reading from cin will automatically cause a flush of cout.

cout << "Cola Machine V1\n"
        "1. Coca-Cola\n"
        "2. Sprite\n"
        "3. Fanta\n"
        "4. Mountain Dew\n"
        "5. Pepsi\n"
        "Pick your favorite beverage: ";

Answer 2

I would build a closely-coupled mapping between the item and the message, which makes it easier to add, remove, and reorder items without things going screwy. For a really simple example:

struct Beverage {
    const std::string name;
    const std::string message;
    Beverage(const std::string& name, const std::string& message):
        name(name),
        message(message)
    {}
};

int main() {
    Beverage choices[5] = {
        Beverage("Coca-Cola", "I don't like Coke"),
        Beverage("Sprite", "Too much sugar"),
        // ...
    };

    for (int i = 0; i < 5; i++) {
        std::cout << i + 1 << ": " << choices[i].name << std::endl;
    }

    int selected;
    std::cin >> selected;
    if (selected >= 1 && selected <= 5) {
        std::cout << choices[selected - 1].message << std::endl;
    } else {
        std::cout << "Invalid choice" << std::endl;
    }

    return 0;
}

Obviously this is not the overall program structure, but an example of how to make a closer coupling between the choices and responses.

Answer 3

Yet another way of performing the dispatch according to a user selection would be with an array of strings. Or better still, with an std::array, assuming your compiler is C++11 capable (which is probably the case):

// Add these somewhere:
#include <array>
#include <string>

...

const std::array<std::string, 5> choices = {
    "I don't like Coca-Cola...",
    "Sprite is ok I guess.",
    "Waayyyy too much sugar.",
    "Mountain Dew! Nice.",
    "Eww. People don't drink Pepsi these days, it ain't the 90's."
};

if (UserSodaChoice >= 1 && UserSodaChoice <= choices.size())
{
    cout << choices[UserSodaChoice - 1];
}
// Else, handle invalid input...

Notice the - 1 when indexing the array. This is because UserSodaChoice ranges from 1 to 5, while the array range is 0 to N-1.

Answer 4

Just something minor:

I would suggest using a switch statement instead of multiple if statements.

switch(UserSodaChoice){

case 1:
    cout << "I don't like Coca-Cola...";
    break;
case 2:
    cout << "Sprite is ok I guess.";
    break;
case 3:
    cout << "Waayyyy too much sugar.";
    break;
case 4:
    cout << "Mountain Dew! Nice.";
    break;
case 5:
    cout << "Eww. People don't drink Pepsi these days, it ain't the 90's.";
    break;
default:
    cout << "Error.\n";
    break;
}
cout << "\n\n\n\t\t\t";

NOTE: I won't be creating a switch statement or making a error message...

Oops, sorry. For some reason I did not see this. I guess that would make my review useless to you, but I don't think it is completely moot.

Answer 5

Using C++11

// some includes you can figure out
...
// good choice for adding to the global name space.
using std::cout;
using std::cin;
using std::endl;

// Use predefined data structures (STL) when possible
// they are usually less error prone and sometimes faster.
using Products = std::pair<std::string, std::string>;

// Don't use magic numbers like 5 or use some const to describe them.
// Use resizeable arrays like vector unless the size is set in stone, which
// vending machines aren't, adding Coke-Lite gives fewer problems this way.
std::vector<Products> brands {
    { "Coca-Cola", "I don't like Coca-Cola..." },
    { "Sprite", "Sprite is ok I guess." },
    { "Fanta", "Waayyyy too much sugar." },
    { "Mountain Dew", "Mountain Dew! Nice." },
    { "Pepsi", "Eww. People don't drink Pepsi these days, it ain't the 90's." }
};

void DisplayMenu() {
    int count = 0;

    cout << "Cola Machine V1" << "\n";
    for(auto prod: brands)
        cout << ++count << ". " << prod.first << "\n";

    cout << "Pick your favorite beverage: ";
}

int Vending() {
    // always initialize your variables,
    // even if you ATM can see they don't need it
    int UserSodaChoice = 0;

    DisplayMenu();  // reduce code clutter by using functions

    cin >> UserSodaChoice;

    // ToDo in V2 validate UserSodaChoice
    auto prod = brands[UserSodaChoice-1];
    cout << prod.first << ": " << prod.second << endl;

    return UserSodaChoice;
}

int main() {
    return Vending(); // do something fantastic with the return value
}

If you are learning to use classes later then you can easily transform it into a class as the structure is already there.

Answer 6

Flush your output.. And use if else... Instead of using just and if statement.. Using if else.. Reduces the execution time of your program... NOTE: using a structure further simplifies your program.

Also use a do while loop..

do
{ 
    //Print ur menu... 
    //Ask the user if he wants to select again..
}
while ( condition) 

This will make the program look professional.. Also include a clear screen (clrscr()) within the do while..