How to correctly assign a local value to a variable in C#?

Question

C++ / C#

Good evening!
I am writing my second curriculum in C# - a console calculator.
The goal is this:

• The user enters the first number, then he enters the operand to further enter the second number and get the result
  

And before testing the program, the compiler displayed this information:
Use of the local variable "result", which has not been assigned a value. [csharp-dotnetcore-calculator]
And here is an example of the code for the console calculator itself:

using System;
namespace csharp_dotnetcore_calculator
{
    class Program
    {
        public static float add(float first,float second)
        {
            return first + second;//Сложение
        }
        public static float subtraction(float first,float second)
        {
            return first - second;//Вычитание
        }
        public static float multiplication(float first,float second)
        {
            return first * second;
        }
        public static float division(float first,float second)
        {
            return first / second;
        }

        static void Main(string[] args)
        {
            Console.WriteLine("Добро пожаловать в калькулятор!");
            while (true)
            {
                Console.WriteLine("Введите первое число:");
                float f = float.Parse(Console.ReadLine());
                Console.WriteLine("Введите операнд(+,-,*,/):");
                string o = Console.ReadLine();
                Console.WriteLine("Введите второе число:");
                float s = float.Parse(Console.ReadLine());
                float result;
                if (o == "+")
                {
                    result = add(f, s);
                }
                else if(o == "-")
                {
                    result = subtraction(f, s);
                }
                else if(o == "*")
                {
                    result = multiplication(f, s);
                }
                else if(o == "/")
                {
                    result = division(f, s);
                }

                string value = $"Результат: {result}";
                Console.WriteLine(value);




                
            }
        }
    }
}

Tell us how to correctly assign a value to a local variable so that the problem is solved?
Thank you in advance!

Answer 1

float result;
If the user enters something other than { +, -, *, / } as an operation, undefined behavior will result. result will not be initialized at the moment Either do Or (which is more correct) - do not allow the possibility of such a situation at all
string value = $"Результат: {result}";
float result = 0f;

if (o == "+")
                {
                    result = add(f, s);
                }
                else if(o == "-")
                {
                    result = subtraction(f, s);
                }
                else if(o == "*")
                {
                    result = multiplication(f, s);
                }
                else if(o == "/")
                {
                    result = division(f, s);
                }
                else
                      throw new Exception($"Unexpected operation '{o}'");

Answer 2

Do as in the calculator the first variable is the result of the second and third operations and the entered value.