C# Number 12

Question

When I run the code it says that * can’t be applied to a string but I thought I converted it. What do I do?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
const double pi = 3.14;
double radius = Convert.ToDouble(Console.ReadLine());

Console.Write("+pi+"*"+radius+"*"+radius+");
}
}
}

Answer 1

You don't need quotes or plus signs in the last line, just pi*radius*radius.

Your code right now says multiply these 3 strings (which just happen to contain the names of your variables, enclosed in plus signs)

Answer 2

Just as Benjamin said this code tries to multiply 3 strings it's like ("+pi+") * ("+radius+") * ("+radius+")
Since it can't multiply strings it throws an error. The Write function can take numbers as an output so just type Console.Write(pi*radius*radius);

Answer 3

Print only the result . Either directly or give it in a variable and print

Answer 4

Math.PI
https://docs.microsoft.com/en-us/dotnet/api/system.math.pi?view=net-5.0

Math.Pow
https://docs.microsoft.com/en-us/dotnet/api/system.math.pow?view=net-5.0

If you want to use .net framework.
You can use Math Class.
You'll get.

double input = Convert.ToDouble(Console.ReadLine());
double radius = Math.Pow(input,2);
Console.Write(Math.Round((Math.PI * radius),2));
Console.ReadKey();

🌻😊🌼

Answer 5

Reconsider that last Console.Write command. I think the quotes don’t line up the way you want them too. It looks like you are trying to multiply three strings together. I can’t tell if those are single quotes or double quotes, but either way it’s a little off.

Answer 6

Bad code 🐷 moon a. 🐽 ; confusing because it doesn't distinguish between the actual radius and it's power.

Answer 7

you don't need quotes because It's want to multiple string and IT CAN'T TO IT!!!!!!!!