[Solved] C# : multiplication identity, How do i get it to do that? [closed]

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First, there appears to be a typo in your question. Apparently your formula isn’t A^2-B^2=(A-B)+(A+B), as the beginning of your question suggests; the example shown is doing multiplication on the right-hand side of the equation.

Here’s a very basic example of how to do this.

int a = ReadInt("Enter value for A: "); // see end of answer for `ReadInt` definitions
int b = ReadInt("Enter value for B: ");

Console.WriteLine("{0}^2-{1}^2=({0}-{1})*({0}+{1})", a, b);
Console.WriteLine("{0}-{1} = ({2})*({3})", a * a, b * b, a - b, a + b);
Console.WriteLine("{0} = {1}", a * a - b * b, (a - b) * (a + b));

The {0}, {1}, etc. in the output text are placeholders. They are explained in the MSDN article “Composite Formatting”. Basically, the zero-based numbers inside the curly brackets specify which of the arguments after the format text (first argument to Console.WriteLine) will be printed in their place.

The above code makes a reference to some ReadInt method. Here are two possible definitions for it:

  • Unsafe, non-validating variant which will throw an exception if the users enters something other than an in-range integral number:

    static int ReadInt(string prompt)
{
    Console.Write(prompt);
    return int.Parse(Console.ReadLine());
}

  • Safer, validating variant:

    static int ReadInt(string prompt)
{
    for (;;)
    {
        Console.Write(prompt);
        int result;
        if (int.TryParse(Console.ReadLine(), out result))
        {
            return result;
        }
        else
        {
            Console.WriteLine("Invalid input! Please enter an integral number.");
        }
    }
}

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solved C# : multiplication identity, How do i get it to do that? [closed]