index was outside the bounds of array

[qjmigo]

Hi! I want to ask if anyone can help me with my problem. I'm trying to write a program for an address book in C# using arrays.I'm still in the beginning and already have a problem.
This is the code i've written so far :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace ConsoleApplication1
{
    class Hope
    {
        static void Main(string[] args)
        {
            string str1, str2, str3, str4, str5;
 
            Console.WriteLine("Enter Family name");
            string s1 = Console.ReadLine();
 
            Console.WriteLine("Enter first name");
            string s2 = Console.ReadLine();
 
            Console.WriteLine("Enter road number");
            string s3 = Console.ReadLine();
 
            Console.WriteLine("Enter road name");
            string s4 = Console.ReadLine();
 
            Console.WriteLine("Enter town name");
            string s5 = Console.ReadLine();
 
            string[,] addressBook = { { s1 }, { s2 }, { s3 }, { s4 }, { s5 } };
 
            for (int i = 0; i < addressBook.Length / 2; i++)
            {
                str1 = addressBook[i, 0];
                str2 = addressBook[i, 1];
                str3 = addressBook[i, 2];
                str4 = addressBook[i, 3];
                str5 = addressBook[i, 4];
 
                Console.WriteLine(" {0}, {1}, {2}, {3}, {4} ", str1, str2, str3, str4, str5);
                Console.ReadLine();
            }
            Console.WriteLine();
 
        }
    }
}

In the for loop when the program goes to this line

                str2 = addressBook[i, 1];

it breaks and shows me this message "Index was outside the bounds of the array."

I can't understand why it's happening and can't figure out a way to fix it.

I'll be happy for any help you can give me .
P.S. I'm a novice with C#.

[adriancs]

well, "string[,]" is double array.
single array, "string[]" is good enough.
try this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string str1, str2, str3, str4, str5;
 
            Console.Write("Enter Family name: ");
            string s1 = Console.ReadLine();
 
            Console.Write("Enter first name: ");
            string s2 = Console.ReadLine();
 
            Console.Write("Enter road number: ");
            string s3 = Console.ReadLine();
 
            Console.Write("Enter road name: ");
            string s4 = Console.ReadLine();
 
            Console.Write("Enter town name: ");
            string s5 = Console.ReadLine();
 
            string[] addressBook = { s1, s2, s3, s4, s5 };
 
            for (int i = 0; i < addressBook.Length; i++)
            {
                str1 = addressBook[0];
                str2 = addressBook[1];
                str3 = addressBook[2];
                str4 = addressBook[3];
                str5 = addressBook[4];
 
                Console.WriteLine("\nResult: {0}, {1}, {2}, {3}, {4} ", str1, str2, str3, str4, str5);
                Console.ReadLine();
            }
            Console.WriteLine();
        }
    }
}

if you wish to store more than 1 record dynamically, you can use "List<>".

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string[]> lst = new List<string[]>();
 
            bool ExitProgram = false;
 
            while (!ExitProgram)
            {
                Console.Clear();
                Console.WriteLine("Total records: " + lst.Count);
                Console.WriteLine("\nAdd new record\n");
                string str1, str2, str3, str4, str5;
 
                Console.Write("Enter Family name: ");
                string s1 = Console.ReadLine();
 
                Console.Write("Enter first name: ");
                string s2 = Console.ReadLine();
 
                Console.Write("Enter road number: ");
                string s3 = Console.ReadLine();
 
                Console.Write("Enter road name: ");
                string s4 = Console.ReadLine();
 
                Console.Write("Enter town name: ");
                string s5 = Console.ReadLine();
 
                string[] addressBook = { s1, s2, s3, s4, s5 };
 
                lst.Add(addressBook);
 
                Console.WriteLine();
 
                for (int i = 0; i < lst.Count; i++)
                {
                    str1 = addressBook[0];
                    str2 = addressBook[1];
                    str3 = addressBook[2];
                    str4 = addressBook[3];
                    str5 = addressBook[4];
 
                    Console.WriteLine("Record " + (i + 1) + ": {0}, {1}, {2}, {3}, {4} ", str1, str2, str3, str4, str5);
                }
                Console.Write("\nPress any key to continue, or [Q] to exit: ");
 
                string nextTask = Console.ReadLine().ToUpper();
 
                if (nextTask == "Q")
                    ExitProgram = true;
            }
        }
    }
}

[qjmigo]

Thanks adriancs! This is really helpful but can you tell me why str2 = addressBook[i, 1]; is out of the bounds if the array? I can't figure that out and I want to understand it so I won't make the same mistake in the future.

[adriancs]

Hi, qjmigo,

lets say, we create 5 strings:

string a1, b1, c1, d1, e1;

because this >> "[,]" is only 2 dimensional array, we can understand it with a 2-D graph.
for example, columns and rows.

so, if we initialize the string array with this:

string[,] addressBook = { { a1 }, { b1 }, { c1 }, { d1 }, { e1 } };

will create 5 rows with 1 column. Lets asume Y = row, and X = column.

    X1
Y1    a1
Y2    b1
Y3    c1
Y4    d1
Y5    e1

as you can see, addressBook only contains 5 strings.
results:

addressBook.Length = 5;
addressBook[0,0] = a1;
addressBook[3,0] = d1;

lets try another example. We initialize the string array with this:

string a1, a2, a3, b1, b2, b3, c1, c2, c3, d1, d2, d3, e1, e2, e3;
string[,] addressBook = { { a1, a2, a3 }, { b1, b2, b3 }, { c1, c2, c3 }, { d1, d2, d3 }, { e1, e2, e3 } };

this will create 5 rows and 3 columns,

    X1    X2    X3
Y1    a1    a2    a3
Y2    b1    b2    b3
Y3    c1    c2    c3    
Y4    d1    d2    d3
Y5    e1    e2    e3

Results:

addressBook.Length = 15;
addressBook[0,0] = a1;
addressBook[2,1] = c2;
addressBook[4,2] = e3;
addressBook[5,0] = outside the bounds of array, there is no Row 6.
addressBook[0,3] = outside the bounds of array, there is no Column 4.

now we come back to your codes, this block:

for (int i = 0; i < addressBook.Length / 2; i++)
{
 
}

in this case:

string[,] addressBook = { { s1 }, { s2 }, { s3 }, { s4 }, { s5 } };
addressBook.Length = 5;

which means:

for (int i = 0; i < (5 / 2); i++)
{
 
}

then

addressBook[i, 0]; << exist
addressBook[i, 1]; << there is no column 2
addressBook[i, 2]; << there is no column 3
addressBook[i, 3]; << there is no column 4
addressBook[i, 4]; << there is no column 5

and because your loop condition is " i < (5 / 2) "
this "for loop" will have at least 3 loops.
first loop, i = 0
this loop is ok. the number zero refers to first row.
but start from 2nd loop, i = 1, refers to 2nd row.
but there is no 2nd row, thus, create another error >> outside the bounds of array.
3rd loop, i = 2, refers to 3rd row.
>> outside the bounds of array. There is no row 3.

[qjmigo]

adriancs that is a really rich answer! Now I understand where is the problem. Thanks a lot! :-)

[adriancs]

Hi, you are welcome.

by the way, you may consider to mark "choose as best answer button" on the most appropriate post that has solved your problems. :-)
thanks