C# user input int to array

Question

I'm asking the user to input 5 numbers and store it into an array so I can send the values in a method and subtract 5 numbers from each array. When I use the:

for(I=0;I<5;I++) {
int[] val = Console.ReadLine();}

It says I can't convert int[] to int. I'm a little rusty in my programming. I also don't know how to send the array values from the main to the method.

Answer 1

You're assigning the string input from the Console to an array of int. This is wrong for two reasons:

1. int arrays (int[]) are a collection of ints.
2. The value you're getting from the Console isn't an int and needs to be parsed first.

This is a slight diversion, but I also don't think you should be using an array. Arrays generally have significantly less function in C# than the built-in List<T>. (All the rockstars chime in here) Some people say there's no reason to use arrays at all - I won't go that far, but I think for this use case it'll be a lot easier to just add items to a List than to allocate 5 spaces and initialize values by index.

Either way, you should use int.TryParse(), not int.Parse(), given that you'll immediately get an exception if you don't check if the user input was parseable to int. So example code for taking in strings from the user would look like this:

List<int> userInts = new List<int>();

for (int i = 0; i < 5; i++)
{
    string userValue = Console.ReadLine();
    int userInt;
    if (int.TryParse(userValue, out userInt))
    {
        userInts.Add(userInt);
    }
}

If you'd still like to use the array, or if you have to, just replace List<int> userInts... with int[] userInts = new int[5];, and replace userInts.Add(userInt) with userInts[i] = userInt;.

Answer 2

You initialize the array first

int[] val = new int[5];

and then when you do a for loop:

for (int i=0; i<val.Length; i++)
{
   val[i] = int.Parse(Console.ReadLine());
}

Hint: To send the array values from main to the method, just look at how static void main is formed:

static void Main(string[] args)

Meaning main is accepting a string array of of console arguments.

Answer 3

1. First initialize your array to have size 5:

int[] array = new int[5];

2. Then loop through the array to store each input:

    for (int i=0; i<array.Length; i++)
    {
        array[i] = Convert.ToInt32(Console.ReadLine());
    }

3. Finally, you need to pass your array as an argument to the method.

Note : There are several ways to create a method.
Visit this page to know about methods and how they are called from Main().

Answer 4

You just need to parse the string being entered from the console to int first.You accept int by doing:

for(int i=0;i<myArray.Length;i++) {

  myArray[i] = int.Parse(Console.ReadLine()); //Int32.Parse(Console.ReadLine()) also works

Just like @Furkle said, it is always best to use TryParse() which enables you to perform exception handling. MSDN has a nice tutorial on this.

Answer 5

furkle is correct, it's not working because the console.ReadLine method returns a string, and you can't assign a string to an int array. However, the solution provided is a bit clunky because it only reads one character at a time from the console. It's better to take in all the input at once.

Here is a short console program that

• takes in a space separated list of integers from the user
• converts the string to a string List using Split(' ').ToList();
• Converts the string List to an int List
• Reads the contents back to you.

Error handling is included.

    static void Main(string[] args){

    var intList = new List<int>();
    string sUserInput = "";
    var sList = new List<string>();
    bool validInput = true;

    do
    {
        validInput = true;
        Console.WriteLine("input a space separated list of integers");
        sUserInput = Console.ReadLine();
        sList = sUserInput.Split(' ').ToList();

        try
        {
            foreach (var item in sList) {intList.Add(int.Parse(item));}
        }
        catch (Exception e)
        {
            validInput = false;
            Console.WriteLine("An error occurred. You may have entered the list incorrectly. Please make sure you only enter integer values separated by a space. \r\n");
        }
    } while (validInput == false);

    Console.WriteLine("\r\nHere are the contents of the intList:");
    foreach (var item in intList)
    {
        Console.WriteLine(item);
    }

    Console.WriteLine("\r\npress any key to exit...");
    Console.ReadKey();
    }//end main

If you want to make sure the user only enters a total of 5 integers you can do the DO WHILE loop like this:

    do
    {
        validInput = true;
        Console.WriteLine("input a space separated list of integers");
        sUserInput = Console.ReadLine();
        sList = sUserInput.Split(' ').ToList();

        if (sList.Count > 5)
        {
            validInput = false;
            Console.WriteLine("you entered too many integers. You must enter only 5 integers. \r\n");
        }
        else
        {
            try
            {
                foreach (var item in sList) { intList.Add(int.Parse(item)); }
            }
            catch (Exception e)
            {
                validInput = false;
                Console.WriteLine("An error occurred. You may have entered the list incorrectly. Please make sure you only enter integer values separated by a space. \r\n");
            }
        }

    } while (validInput == false);