nothing is happening in the terminal

[gabzz29]

every time i enter an int in the terminal nothing is happening , then after i spam a few int it will show result but its wrong

  #include <iostream>
using namespace std;

int main (){
    cout << "Calculator 2.0";
    char again = 'Y';

    while(again == 'y' || again == 'Y'){
        double x,y,ans;
        int op;
        cout << "1.Addition\n";
        cout << "2.Substraction\n";
        cout << "3.Multiplication\n";
        cout << "4.Division\n";
        cout << "Enter an operation:";
        cin >> op;
        cout << "Enter two digits:";
        cin >> x >> y;

        while(!(cin >> op)){
            cout << "Only choose above choices:";
            cin.clear();
            cin.ignore(100, '\n');
        }

        while(!(cin >> x >> y)){
            cout << "Must be a number:";
            cin.clear();
            cin.ignore(100, '\n');
        }

        switch(op){
            case 1:
            ans = x + y;
            cout << x << " + " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
            case 2:
            ans = x - y;
            cout << x << " - " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
            case 3:
            ans = x * y;
            cout << x << " * " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
            case 4:
            ans = x / y;
            cout << x << " / " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
        }


    }
}

[kigar64551]

Note that std::istream::operator>>(int& val) does not simply read a single digit or character. It reads a sequence of characters (which usually ends when the user hits enter). The char sequence as a whole will then be converted into an int value.

https://cplusplus.com/reference/istream/istream/operator%3E%3E/

Note: You might want to look into std::istream::get(char& c) for reading a single character.

[mbozzi]

You've tried to read op then x and y twice in a row. Swap lines 17 and 25. Then delete line 16 and 18.

#include <iostream>
using namespace std;

int main (){
    cout << "Calculator 2.0";
    char again = 'Y';

    while(again == 'y' || again == 'Y'){
        double x,y,ans;
        int op;
        cout << "1.Addition\n";
        cout << "2.Substraction\n";
        cout << "3.Multiplication\n";
        cout << "4.Division\n";
        cout << "Enter an operation:";
        // cin >> op;

        // cin >> x >> y;

        while(!(cin >> op)){
            cout << "Only choose above choices:";
            cin.clear();
            cin.ignore(100, '\n');
        }
        cout << "Enter two digits:";
        while(!(cin >> x >> y)){
            cout << "Must be a number:";
            cin.clear();
            cin.ignore(100, '\n');
        }

        switch(op){
            case 1:
            ans = x + y;
            cout << x << " + " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
            case 2:
            ans = x - y;
            cout << x << " - " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
            case 3:
            ans = x * y;
            cout << x << " * " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
            case 4:
            ans = x / y;
            cout << x << " / " << y << " = " << ans;
            cout << "Calculate again? [Y/N]";
            cin >> again;
            break;
        }


    }
}

[gabzz29]

thank you everyone!

[seeplus]

Why have "Calculate again" at the end of every case? Why not have after the switch? Also, there's no error output if an invalid operator is entered.

while(!(cin >> op) || (op < 1 || op > 4)){

Also, there's no check for division by 0 - which will cause a run-time error.

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

int main() {
	cout << "Calculator 2.0\n\n";

	for (char again = 'Y'; again == 'y' || again == 'Y'; ) {
		double x, y, ans;
		int op;

		cout << "1. Addition\n";
		cout << "2. Substraction\n";
		cout << "3. Multiplication\n";
		cout << "4. Division\n";

		cout << "Enter an operation (1 - 4): ";
		while (!(cin >> op) || (op < 1 || op > 4)) {
			cout << "Only choose above choices: ";
			cin.clear();
			cin.ignore(100, '\n');
		}

		cout << "Enter two digits: ";
		while (!(cin >> x >> y)) {
			cout << "Must be 2 numbers: ";
			cin.clear();
			cin.ignore(100, '\n');
		}

		switch (op) {
			case 1:
				ans = x + y;
				cout << x << " + " << y;
				break;

			case 2:
				ans = x - y;
				cout << x << " - " << y;
				break;

			case 3:
				ans = x * y;
				cout << x << " * " << y;
				break;

			case 4:
				if (y != 0) {
					ans = x / y;
					cout << x << " / " << y;
				} else {
					ans = NAN;
					cout << "Attempted division by 0";
				}
				break;
		}

		cout << " = " << ans << '\n';
		cout << "Calculate again [Y/N]: ";
		cin >> again;
	}
}