How to invert a positive number to negative and vice versa in C#?

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How do I get the number typed by the user, whether positive or negative, reversed?

using System;

namespace POOTeste
{
    class Program2
    {
        static int Main(string[] args)
        {
            int numero;
            Console.Write("Digite um número positivo ou negativo: ");
            numero = int.Parse(Console.ReadLine());
            Console.Write($"O valor inverso é {numero}");
            Console.ReadKey();
            return 0;
        }
    }
}
c# .net mathematics operators

  • You can multiply by -1 to reverse its value, and check if it is negative with < 0.

1 answer

2


Placing the equal negative sign (-) in mathematics. It also seems that you have not yet learned to pick up a number typed correctly, as I have answered you before (it can give a more significant error message or make a loop to ask again if the person has typed something wrong). Then the right thing would be:

using static System.Console;

namespace POOTeste {
    public class Program2 {
        public static int Main() {
            Write("Digite um número positivo ou negativo: ");
            if (!int.TryParse(ReadLine(), out var numero)) return 1;
            Write($"O valor inverso é {-numero}");
            return 0;
        }
    }
}

Behold working in the ideone. And in the .NET Fiddle. Also put on the Github for future reference.

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