如何使用 StreamReader 读取 C#.

Question

I'm trying to read a string with StreamReader, so I don't know how to read it.

using System;
using System.Diagnostics;
using System.IO;
using System.Text;

namespace 
{
    class Program
    {
        static void Main(string[] args)
        {
            string itemCostsInput = "25.34\n10.99\n250.22\n21.87\n50.24\n15";
            string payerCountInput = "8\n";
            string individualCostInput = "52.24\n";

           
                double individualCost = RestaurantBillCalculator.CalculateIndividualCost(reader2, totalCost);
                Debug.Assert(individualCost == 54.14);

                uint payerCount = RestaurantBillCalculator.CalculatePayerCount(reader3, totalCost);
                Debug.Assert(payerCount == 9);
            }
        }
    }
}

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

using System.IO;

namespace as
{
    public static class RestaurantBillCalculator
    {

        public static double CalculateTotalCost(StreamReader input)
        {

//  I want to read the input (not System.IO.StreamReader, 

25.34
10.99
250.22
21.87
50.24
15

//below is what i tried..
            int[] numbers = new int[6];
            for (int i = 0; i < 5; i++)
            {
                numbers[int.Parse(input.ReadLine())]++;

            }


            for (int i = 0; i < 5; i++)
            {
                    Console.WriteLine(numbers[i]);
            }


            return 0;
        }
       

        public static double CalculateIndividualCost(StreamReader input, double totalCost)
        {
            return 0;
        }

        public static uint CalculatePayerCount(StreamReader input, double totalCost)
        {
            return 0;
        }
    }
}

Even when I googled it, only file input/output came up with that phrase.

I want to get a simple string and read it.

int[] numbers = new int[6]; // The number at the index number

// take the given numbers
for (int i = 0; i < n; i++)
{
    numbers[int. Parse(sr. ReadLine())]++;
}

I tried the above method, but it didn't work.

I just want to get the index and read the contents of itemCostsInput as it is. If I just execute Console.writeLine, String == System.IO.StreamReader

comes out I want to read and save the values of itemCostsInput respectively. I just want to do something like read.

I'm sorry I'm not good at English

I expected input Read

25.34
10.99
250.22
21.87
50.24
15

but console print System.IO.StreamReader

Answer 1

This lines are the ones causing (more) trouble I think:

        for (int i = 0; i < 5; i++)
        {
            numbers[int.Parse(input.ReadLine())]++;

        }

Should be

        for (int i = 0; i < 5; i++)
        {
            numbers[i] = int.Parse(input.ReadLine());

        }

But since you have a decimal input (in string format due to the streamreader), maybe numbers should be an array of decimals.

Also there are quite a few remarks about the use of StreamReader, since if the file doesn't have 5 or more lines, your program will also break. I let this here hoping will clarify something to you, though

Answer 2

Your code does not make sense in its current state.
Please read up on Streams .

Usually you'd get a stream from a file or from a.network connection but not from a string.
You are confusing integer and double.
The double data type represents floating point numbers.

It seems to me that you just started programming and are missing out on most of the fundamentals.

First, convert your string input into a stream:

static System.IO.Stream GetStream(string input)
{
    Stream stream = new MemoryStream();
    StreamWriter writer = new StreamWriter(stream);
    writer.Write(input);
    writer.Flush();
    stream.Position = 0;

    return stream;
}

Now you can convert your input to a stream like this:

// ... code ...

string itemCostsInput = "25.34\n10.99\n250.22\n21.87\n50.24\n15";
var dataStream = GetStream(itemCostsInput);

// ... code ...

Now you that you converted your string input into a stream you can start to parse your data and extract the numbers:

static List<double> GetDoubleFromStream(Stream stream)
{
    if (stream == null) {
        return new List<double>();
    }

    const char NEWLINE = '\n';

    List<double> result = new List<double>();
    using (var reader = new StreamReader(stream)) 
    {
        // Continue until end of stream has been reached.
        while (reader.Peek() > -1) 
        {
            string temp = string.Empty;
            // Read while not end of stream and char is not new line.
            while (reader.Peek() != NEWLINE && reader.Peek() > -1)  {
                temp += (char)reader.Read();
            }
            // Perform another read operation 
            // to skip the current new line character
            // and continue reading.
            reader.Read();

            // Parse data to double if valid.
            if (!(string.IsNullOrEmpty(temp))) 
            {
                double d;
                // Allow decimal points and ignore culture.
                if (double.TryParse(
                    temp, 
                    NumberStyles.AllowDecimalPoint, 
                    CultureInfo.InvariantCulture, 
                    out d)) 
                {
                    result.Add(d);
                }
            }
        }
    }
    return result;
}

This would be your intermediate result: Now you can convert your input to a stream like this:

// ... code ...

string itemCostsInput = "25.34\n10.99\n250.22\n21.87\n50.24\n15";
var dataStream = GetStream(itemCostsInput);
var result = GetDoubleFromStream(dataStream);
// ... code ...