Populating an array with user input of size not working in C#

Question

I want to let the user define the size of the array and all of the numbers inside it, so this is what I had in mind:

int []arr={0};
Console.WriteLine("Please enter the size of the array:");
size = Console.Read();

for(int i=0; i<size; i++)
{
    Console.WriteLine("Please enter the next number in the array, it's position is: " + i);
    arr[i] = Console.Read();
}

When I try to run it gives me an 'index out of range' error. If someone could point what am I doing wrong I would really appreciate it.

EDIT: After the answer I changed the code a little bit and now it looks like this:

Console.WriteLine("Please enter the size of the array:");
input = Console.ReadLine();
size = int.Parse(input);
int[] arr = new int[size];

for(int i=0; i<size; i++)
{
    string b;
    Console.WriteLine("Please enter the next number in the array, it's position is: " + i);
    b = Console.ReadLine();
    arr[i] = int.Parse(b); 
}

So now the array can be bigger and so does the numbers inside, thanks again for the help!

The first line of your code creates an array with the length of 1. Your size variable is not used to initialize the array. — dugas
– dugas, Commented Jan 27, 2016 at 20:03

Shaharyar · Accepted Answer · 2016-01-27 20:10:53Z

3

You need to initialize the array after getting input from user:

Console.WriteLine("Please enter the size of the array:");
int size = int.Parse(Console.ReadLine()); //you need to parse the input too
int[] arr = new int[size];

for(int i=0; i < arr.Length; i++)
{
    Console.WriteLine("Please enter the next number in the array, it's position is: " + i);
    arr[i] = int.Parse(Console.ReadLine()); //parsing to "int"
}

Note: You should not use Console.Read() it returns an ASCII of the character as Szabolcs Dézsi mentioned in the comments. You should use Console.ReadLine() instead.

edited Jan 27, 2016 at 20:10

answered Jan 27, 2016 at 20:00

Shaharyar

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3 Comments

Szabolcs Dézsi Over a year ago

Console.Read returns int, so you don't need to parse it. And I wouldn't recommend it to read in the size of the array, it returns the ASCII code of the character.

Shaharyar Over a year ago

Thanks for the info, will correct the answer for sure.

Miguel R Over a year ago

Hey man thank for the help, I reworked the code and now it's all working.

user2723342 · Accepted Answer · 2016-01-27 20:07:06Z

0

You need to re-instantiate your array object:

int []arr={0};
Console.WriteLine("Please enter the size of the array:");
size = Console.Read();
arr=new int[size];
for(int i=0; i<size; i++){
   Console.WriteLine("Please enter the next number in the array, it's position is: " + i);
   arr[i] = Console.Read();
            }

answered Jan 27, 2016 at 20:07

user2723342

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Comments

Szabolcs Dézsi · Accepted Answer · 2016-01-27 20:13:02Z

Still not the most ideal, but this will prevent the user from entering non-numeric data. Keeps prompting each time until the data is valid.

Console.WriteLine("Please enter the size of the array:");
int size;

while(!int.TryParse(Console.ReadLine(), out size))
{
    Console.WriteLine("Please enter the size of the array:");
}

var arr = new int[size];

for (int i = 0; i < size; i++)
{
    Console.WriteLine("Please enter the next number in the array, it's position is: " + i);
    int currentElement;
    while (!int.TryParse(Console.ReadLine(), out currentElement))
    {
        Console.WriteLine("Please enter the next number in the array, it's position is: " + i);
    }

    arr[i] = currentElement;
}

I would not use Console.Read, because with that you can only read one character at a time. So at most you can only read 0-9 for the array size, and if you enter lets say 15, the length of the array will be 1, and the next Read will read 5 and fill in the first element.

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