Nicely print Calculator input along with the result

Question

How can I output the number, the operator, and the result at once. After the user input

double answer;

WriteLine("Enter your first number");
double num1 = Convert.ToDouble(Console.ReadLine());

string sign;
WriteLine("Enter any of the following operators (+,-,*,/ )");
sign = Console.ReadLine();

WriteLine("Enter your second number");
double num2 = Convert.ToDouble(Console.ReadLine());

switch (sign)
{
    case "+":
        answer = num1 + num2;
        WriteLine(answer);
        break;
    case "-":
        answer = num1 - num2;
        WriteLine(answer);
        break;
}

Ideally output would look like 12 + 34 = 46, but any variations (including RPN - 12 34 + 46 would do).

Since this is homework for one of the first lessons, please don't push the envelope with suggested answers - while some input validation would be nice avoid lambda expressions and generics as we have not officially studied those.

Answer 1

Here you go, for fun, here's how I would do this:

var calculations = new Dictionary<string, Func<double, double, double>>()
{
    { "+", (x, y) => x + y },
    { "-", (x, y) => x - y },
    { "*", (x, y) => x * y },
    { "/", (x, y) => x / y },
};

double EnterNumber(string message)
{
    while (true)
    {
        Console.WriteLine(message);
        if (double.TryParse(Console.ReadLine(), out double value))
        {
            return value;
        }
    }
}

string EnterOperator(string message)
{
    string sign = null;
    while (true)
    {
        Console.WriteLine(message);
        if ("+-*/".Contains(sign = Console.ReadLine()))
        {
            return sign;
        }
    }
}
double num1 = EnterNumber("Enter your first number");
string sign = EnterOperator("Enter any of the following operators (+,-,*,/ )");
double num2 = EnterNumber("Enter your second number");

Console.WriteLine($"{num1} {sign} {num2} = {calculations[sign](num1, num2)}");

---

Here's a slightly more refactored version to eliminate as much repetition as possible.

var calculations = new Dictionary<string, Func<double, double, double>>()
{
    { "+", (x, y) => x + y },
    { "-", (x, y) => x - y },
    { "*", (x, y) => x * y },
    { "/", (x, y) => x / y },
};

T EnterValue<T>(string message, Func<string, (bool success, T value)> tryParse)
{
    while (true)
    {
        Console.WriteLine(message);
        var output = tryParse(Console.ReadLine());
        if (output.success)
        {
            return output.value;
        }
    }
}

double EnterNumber(string message) => EnterValue<double>(message, x =>
    double.TryParse(x, out double value) ? (true, value) : (false, default));
    
string EnterOperator(string message) => EnterValue<string>(message, x =>
    ("+-*/".Contains(x), x));

double num1 = EnterNumber("Enter your first number");
string sign = EnterOperator("Enter any of the following operators (+,-,*,/ )");
double num2 = EnterNumber("Enter your second number");

Console.WriteLine($"{num1} {sign} {num2} = {calculations[sign](num1, num2)}");

Answer 2

Here it goes:-

 switch (sign) {
        case "+":

            answer = num1 + num2;
            WriteLine(num1+" "+num2+" + "+answer);
          
       break; 


            case "-":
            answer = num1 - num2;
            WriteLine(num1+" "+num2+" - "+answer);
            break;
    }