如何使用 C Sharp 上的指数返回 1、1+1、1+1+1？

Question

I am a rookie using C# trying to figure out how to run a for loop to output 1 on the first iteration, then output 1+1 on the second iteration, 1+1+1 on the third, etc. To solve this, I first put an if statement for the value i = 1 so that it outputs 1 using the equation (i-1) 10^i-1 * 1 then for i>1 I am writing i = 10^(i-1) + 1. However, while I am running the program, it is telling me I have unassigned local variables and that there is no parameter that corresponds to y of Math Pow (double, double). So far I am using Math.Pow to create exponent in C sharp unless there is another easier way of doing so. Not sure what that means? Do you have any suggestions as to how to fix this please?

Thank you so much!

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

/* Equation that helps 
 * i = (n-1)*(10^i-1) + 1 -> works only for i = 1
 * for i>1 i = (10^i-1) + 1 
 */
namespace PL1Week6Part1SumofSeries1_11_111_1111CSharp
{
    internal class Program
    {
        static void Main(string[] args)
        {
        int i, sum;
        double d = Math.Pow(i - 1); 
        sum = 0;
        for (i=1; i >= 1; i++)
            {
                if (i == 1)
                {
                    i = ((i - 1) * 10^(i-1) + 1);
                    Console.Write("{0} +", i);
                    Console.ReadLine();
                }
                else
                {
                    sum = i + sum;
                    i = 10 ^ (i - 1) + 1;
                    Console.Write("{0} +", i);
                    Console.ReadLine();
                }
            }
        }
    }
}

Answer 1

I assume that you want to create a series of 1 s like 1, 11, 111, ... and not add the 1 s. Then you can do this by adding up powers of ten. You don't need a power function for this. Just start with 1 and then multiply this value by 10 at every loop iteration. I will use long , as it has it allows up to 19 digits.

int numberOfDigits = 4; // As an example. Works up to 19.
long sum = 0;
long digit = 1;
for (int i = 0; i < numberOfDigits; i++) {
    sum += digit;
    digit *= 10;
}
Console.WriteLine(sum);

---

A completely different solution creates the 1's series by first calculating a power of 10, eg 10 ⁴ = 10000, then subtracts 1 to get 9999 and finally divides by 9 to get 1111.

int numberOfDigits = 4; // Works up to 18.
Console.WriteLine(((long)Math.Pow(10, numberOfDigits) - 1) / 9);

Both examples print 1111 .