Guess the Number In C++

Question

Mind that this is my first actual program in C++ and I tried to prepare for any possible input. Also the reason I included static_cast<void>(generator(range)) is to throw away the first random value because I read on LearnCpp.com that throwing away the first is a common practice to produce more random results. Anyways here is the code, all suggestions are welcome.

#include <iostream>
#include <limits>
#include <random>

bool validateInput(int input)
{
    using namespace std;

    if (1 <= input && input <= 100)
        return true;
    else if (!input)
        return false;
    else
        return false;
}

int generateRandomNumber()
{
    std::random_device dev;
    std::mt19937_64 range(dev());
    std::uniform_int_distribution<std::mt19937_64::result_type> generator(1, 100);
    static_cast<void>(generator(range));
    return static_cast<int>(generator(range));
}

bool placement(int input, int target)
{
    using namespace std;
    if (input > target)
    {
        cout << "Guess is too high.";
        return false;
    }

    else if (input < target)
    {
        cout << "Guess is too low.";
        return false;
    }
    else
    {
        cout << "Guess is correct!";
        return true;
    }
}

int main()
{
    using namespace std;
    cout << "You have 7 guesses to guess what number I am thinking of between 1 and 100.\n";
    int winning_num{ generateRandomNumber() };
    static int tries{ 1 };
    do
    {
        int num;
        cout << "\nGuess#" << tries << ": Enter a number -> ";
        cin >> num;
        if (!cin)
        {
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
            continue;
        }

        cin.ignore(numeric_limits<streamsize>::max(), '\n');
        
        if (validateInput(num))
            ;
        else
        {
            continue;
        }
        if (!placement(num, winning_num))
        {
            cout << "\nIncorrect!\n";
            ++tries;
        }
        else
        {
            cout << "\nCorrect!\n";
            exit(0);
        }

    }
    while (tries <= 7);
    cout << "\nYou did not guess the number in the alloted amount of guesses :(\nTry Again!\n";


}

Answer 1

I like that your code (read functions) follows Single Responsibility Principle.

And also that you've put the number comparison code in a separate function unlike

• User guesses the number generated by computer
• Computer tries to guess your inputted number

And also that you use static_cast. All are good coding practices!

---

I'd prefer if you do the text printing in the placement function itself and call it something like compare_with_guess. That way, you don't have to return values and use another if-else block in the caller. Also, the output messages can also be controlled all at one place.

Another way is to use struct like:

struct InputNum{
private:
    const int input;
public:
    InputNum(const int num):input(num){};

    int get() const{
        return input;
    }
    bool greater_than(const int target) const {
        return input > target;
    }
    bool less_than(const int target) const {
        return input < target;
    }
    bool equals(const int target) const {
        return input == target;
    }
}

---

Use const whenever possible.

const int winning_num{ generateRandomNumber() };// +1 for {} initialiser syntax. 

void compare_with_guess(const int input, const int guess){ // After making the changes I suggested above.

bool validateInput(const int input){

---

Avoid using namespace std; completely, let alone using it multiple times in the code.

https://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice

---

Answer 2

Well Your code is working fine but there were some extra code which I have removed and now its like this working same as before.
You can have more simple code if you use using namespace std; at the top of you document.

#include <iostream>
#include <limits>
#include <random>
using namespace std;
bool validateInput(int input)
{

    if (1 <= input && input <= 100)
        return true;
    else
        return false;
}

int generateRandomNumber()
{
    random_device dev;
    mt19937_64 range(dev());
    uniform_int_distribution<std::mt19937_64::result_type> generator(1, 100);
    static_cast<void>(generator(range));
    return static_cast<int>(generator(range));
}

bool placement(int input, int target)
{
    if (input > target)
    {
        cout << "Guess is too high.";
        return false;
    }

    else if (input < target)
    {
        cout << "Guess is too low.";
        return false;
    }
    else
    {
        cout << "Guess is correct!";
        return true;
    }
}

int main()
{
    bool end;
    cout << "You have 7 guesses to guess what number I am thinking of between 1 and 100.\n";
    int winning_num{ generateRandomNumber() };
    static int tries{ 1 };
    do
    {
        end=true;
        int num;
        cout << "\nGuess#" << tries << ": Enter a number -> ";
        cin >> num;
        
        if (validateInput(num))
            ;
        else
        {
            continue;
        }
        if (!placement(num, winning_num))
        {
            cout << "\nIncorrect!\n";
            ++tries;
        }
        else
        {
            cout << "\nCorrect!\n";
            exit(0);
        }
        if(tries>7)
        {
            cout<<"\nDo you want to guess more\nnPress y for it and \nPress n for closing\n";
            char guess;
            cin>>guess;
            switch(guess)
            {
                case 'y':
                {
                    cout<<"\nOk Lets go\n";
                    break;
                }
                case 'n':
                {
                    cout<<"\nEnding the program\n";
                    exit(0);
                }
                default:
                {
                    cout<<"\nEnter right choice\n";
                }
                
            }
        }

    }while (end==true);
    cout << "\nYou did not guess the number in the alloted amount of guesses :(\nTry Again!\n";

}

You can also ask from user when he want to do more guesses or want to end the program making the program user friendly.