main.cs(35,34): error CS1041: Identifier expected, `in' is a keyword

Question

I don't know C# but I have homework to convert from Java to C# or C and I have found an online converter, but when I put the code to C# compiler, I get this error

main.cs(35,34): error CS1041: Identifier expected, `in' is a keyword

This is my C# code:

using System;

public class JavaApplication
{
    public static void selectionSort(int[] arr)
    {
        for (int i = 0; i < arr.Length - 1; i++)
        {
            int index = i;

            for (int j = i + 1; j < arr.Length; j++)
            {
                if (arr[j] < arr[index])
                {
                    index = j; //searching for lowest index
                }
            }

            int smallerNumber = arr[index];

            arr[index] = arr[i];
            arr[i] = smallerNumber;
        }
    }

    public static void Main(string[] a)
    {
        int[] arr1 = new int[10];
        Scanner scan = new Scanner(System.in);
        Console.WriteLine("Before Selection Sort:");

        for (int i = 0; i < 10; i++)
        {
            arr1[i] = scan.Next();
        }

        selectionSort(arr1);

        Console.WriteLine("After Selection Sort");

        foreach (int i in arr1)
        {
           Console.Write(i + " ");
        }

        Console.WriteLine("");
        int sumEven = 0;
        int sumOdd = 0;

        for (int j = 0; j < 10; j++)
        {
           if (arr1[j] % 2 == 0)
           {
               sumEven++;
           }
           else
           {
               sumOdd++;
           }
        }

        Console.WriteLine("The number of even numbers in this array is:" + sumEven);
        Console.WriteLine("The number of odd numbers in this array is:" + sumOdd);
    }
}

Presumably it's this line: `Scanner scan = new Scanner(System.in);`. `System.in` doesn't exist in C#. Presumably you'll need to rewrite `Scanner` around using the static `Console` class instead. — ProgrammingLlama, Apr 29 '21 at 07:18
_"can u please write the code"_ - Wouldn't that defeat the point of you doing your homework? — ProgrammingLlama, Apr 29 '21 at 16:06

Martin · Accepted Answer · 2021-04-29T08:01:02.887

1

This line is causing the error:

Scanner scan = new Scanner(System.in);

System.in doesn't mean anything in C#, hence it is complaining because it is looking for a class named in in the System namespace.

In Java console application, System.in is typically the input buffer (keyboard).

In C#, to read a line from the Console, instead of Scanner (which doesn't exist), you can use Console.ReadLine(). Of course it's not clear what is being read in your application (numbers?) so you may need to do some type conversion as ReadLine() returns a string?.

Edit following OP request to read numbers from Console

OP asked how to replace the existing Java code that reads numbers from the console with the C# equivalent. Here is one suggestion (there are several approaches that accomplish the same):

int[] arr1 = new int[10];
Console.WriteLine("Before Selection Sort:");

for (int i = 0; i < 10; i++)
{
    string text = Console.ReadLine();

    if (text != null && int.TryParse(text, out int value))
        arr1[i] = value;
    else
        Console.WriteLine("You must enter a valid number. Try again.");
}

edited Apr 29 '21 at 08:01

answered Apr 29 '21 at 07:17

Martin

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@hananfarhat This is the correct answer to your question. You asked why you are getting the error, this is why. – Martin Apr 29 '21 at 07:27
yes yes i didn't mean that first of all thanks for helping – hanan farhat Apr 29 '21 at 07:28
but i mean the correct typing i mean how to write it since i dont know c# – hanan farhat Apr 29 '21 at 07:28
@hananfarhat What is your code trying to do? Read 10 numbers from the console? – Martin Apr 29 '21 at 07:30
read 10 numbers from console then sorting them form small to big and then put how much even numbers are thier and how mush odd number are thier – hanan farhat Apr 29 '21 at 07:32
@hananfarhat [Reading an integer from user input](https://stackoverflow.com/q/24443827/9363973) – MindSwipe Apr 29 '21 at 07:34
MindSwipe thanks for helping,but martin understands what i want and he is helping – hanan farhat Apr 29 '21 at 07:39
@Martin you understand what I want right? – hanan farhat Apr 29 '21 at 07:57
I've added an example that shows how to achieve this. The link that was helpfully provided by @MindSwipe shows several other methods that achieve the same. – Martin Apr 29 '21 at 08:01
@hananfarhat Have you taken a look at the code I added? – Martin Apr 29 '21 at 08:20
Yes of course ,but i dont want to ask many questions and i am facing problems such as what to replace scan. next with – hanan farhat Apr 30 '21 at 09:29
@hananfarhat You will see in the answer I have shown you have to use `Console.ReadLine()` to replace `scanner`. SO policy is to ask single questions with single answers - if you have another question you should ask it separately – Martin Apr 30 '21 at 09:48
before 7 days i am not allowed to ask – hanan farhat Apr 30 '21 at 10:30
@hananfarhat I'm sorry to hear that but I already answered the question you asked, and then answered the second question you asked. You haven't even marked my answer as correct and are now asking further questions. I can't help you further in this question – Martin Apr 30 '21 at 10:32
sorry i am new to stack – hanan farhat Apr 30 '21 at 11:54

main.cs(35,34): error CS1041: Identifier expected, `in' is a keyword

1 Answers1