Re: Find the smallest integer that is not in a random array - C# Discussion Boards

Error when parsing string as int

31-Mar-22 19:49

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Member 1558328029-Mar-22 5:19

Member 15583280

29-Mar-22 5:19

Hi all,

I am receiving errors when executing below code.
The code asks me how many items the array has, and then let me fill the array with input.
The problem is whenever I input letters instead of numers I get an exception.
System.FormatException: 'Input string was not in a correct format.

The error happens at the following lines

int size = Convert.ToInt32(Console.ReadLine());

array[i] = Convert.ToInt32(Console.ReadLine());

Now I know that I might be using the int.TryParse method, by I do not know how to implement it.
Of perhaps when the input is not valid, give an error like

Console.Write("Wrong input, only numbers");

My code:

//Ask how many array items need to be present
Console.Write("How many items in the array ");
int size = Convert.ToInt32(Console.ReadLine());
int[] array = new int[size];

//Enter array items
Console.WriteLine("Enter {0} array items", size);
for (int i = 0; i < size; i++)
{
    array[i] = Convert.ToInt32(Console.ReadLine());
}

// Print array items
Console.Write("\nThe following items are in the array: ");
for (int i = 0; i < size; i++)
{
    Console.Write("{0} ", array[i]);
}
Console.ReadLine();

Re: Error when parsing string as int

Dave Kreskowiak29-Mar-22 5:33

Dave Kreskowiak

29-Mar-22 5:33

Yeah, you cannot convert strings with letters to an integer since there is no logical conversion.

The documentation on Integer.TryParse can be found here[^] complete with examples and you can even run the example code in the browser and play around with it.

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Find the smallest integer that is not in a random array

Member 1204230226-Mar-22 8:01

Re: Find the smallest integer that is not in a random array

26-Mar-22 8:01

All fine. Thanks.

modified 26-Mar-22 18:18pm.

OriginalGriff26-Mar-22 8:22

Re: Find the smallest integer that is not in a random array

26-Mar-22 8:22

While we are more than willing to help those that are stuck, that doesn't mean that we are here to do it all for you! We can't do all the work, you are either getting paid for this, or it's part of your grades and it wouldn't be at all fair for us to do it all for you.

So we need you to do the work, and we will help you when you get stuck. That doesn't mean we will give you a step by step solution you can hand in!
Start by explaining where you are at the moment, and what the next step in the process is. Then tell us what you have tried to get that next step working, and what happened when you did.

If you are having problems getting started at all, then this may help: How to Write Code to Solve a Problem, A Beginner's Guide[^]

Member 1204230226-Mar-22 8:29

Re: Find the smallest integer that is not in a random array

26-Mar-22 8:29

So how to generate 5 random numbers that fall into the range between 0 and 10000 and assign them to an array? Thanks.

OriginalGriff26-Mar-22 8:46

Re: Find the smallest integer that is not in a random array

26-Mar-22 8:46

Think about it: how do you generate one random number? Hint: see the Random class ...

Get that working, and you can then generate as many as you need.

Get that working, and you can store them in an array.

Get that working, and you can start on the rest of the task.

As the link I originally gave you explains: take a "difficult task" and break it into smaller ones. The smaller ones are "doable" on their own, and doing all of those means you do the "impossible" task as well!
Read the article, and see how far you can get.

Member 1204230226-Mar-22 9:51

Re: Find the smallest integer that is not in a random array

26-Mar-22 9:51

I made the initial code as below:

using System;
 
public class Program
{
    public static void Main(string[] args)
    {
        int N = 10;
        int[] array = new int[N];
        Random rnd = new Random();
        for (int i = 0; i < N; i++)
        {
            array[i] = rnd.Next(10000);
        }
        for (int j = 0; j < N; j++)
        {
            Console.Write(array[j])
        }
    }
}

But it fails to display any code. Can you please help? Thanks.

OriginalGriff26-Mar-22 11:43

Re: Find the smallest integer that is not in a random array

26-Mar-22 11:43

Chances are it does, but it closes down too fast and you can't see it ...
Run it in the debugger, and put a breakpoint on the close curly bracket at the end of the Main method. When you run it, it will stop at the breakpoint and you can see what has happened (or run it again and step through to see what it does while it is running!)

Member 1204230226-Mar-22 12:17

Re: Find the smallest integer that is not in a random array

26-Mar-22 12:17

It works now. The semicolon was missing.

OriginalGriff26-Mar-22 20:05

Re: Find the smallest integer that is not in a random array

26-Mar-22 20:05

If you get an error, it helps if you tell us that, than just assuming we will have seen that on your screen! Laugh | :laugh:

You will be solving syntax errors often - we all do - so this may help you get started: How to Write Code to Solve a Problem, A Beginner's Guide Part 2: Syntax Errors[^]

Richard MacCutchan26-Mar-22 22:32

Richard MacCutchan

26-Mar-22 22:32

Please do not delete your original question, as the full thread could be helpful to other people. Just add "[Solved]" to the message's title.

Inserting Through Radionbutton and checkbox

N Mohamed rafi25-Mar-22 23:20

N Mohamed rafi

25-Mar-22 23:20

My insert code is not working fine, bcz if i click radionbutton2 and checkbox 2 means it was inserting data automatically radionbutton1 and checkbox1 only, actually if which textbox is selected that data should enter null value radionbutton data should not saved in db

if (!string.IsNullOrEmpty(textBox11.Text) && !string.IsNullOrEmpty(textBox12.Text) && !string.IsNullOrEmpty(textBox13.Text) && !string.IsNullOrEmpty(textBox14.Text) && (radioButton1.Checked || radioButton2.Checked) && (checkBox1.Checked || checkBox2.Checked))
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);
cnn.Open();
string id = textBox14.Text;
string name = textBox11.Text;
string year = textBox12.Text;
string quality = radioButton1.Text == "" ? radioButton2.Text : radioButton1.Text;
string taste = checkBox1.Text == "" ? checkBox2.Text : checkBox1.Text;
string sales = textBox13.Text;
textBox11.Text = "";
textBox12.Text = "";
textBox13.Text = "";
textBox14.Text = "";
radioButton1.Text = "";
radioButton2.Text = "";
checkBox1.Text = "";
checkBox2.Text = "";
string query = "INSERT INTO fruits VALUES(@fruitsid, @fruitsname, @fruitsyear, @quality, @taste, @sales)";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@fruitsid", Convert.ToInt32(id));
cmd.Parameters.AddWithValue("@fruitsname", name);
cmd.Parameters.AddWithValue("@fruitsyear", year);
cmd.Parameters.AddWithValue("@quality", quality);
cmd.Parameters.AddWithValue("@taste", taste);
cmd.Parameters.AddWithValue("@sales", sales);
cmd.Connection = cnn;
cmd.ExecuteNonQuery();
MessageBox.Show("Record Inserted Successfully");
DisplayData();
cnn.Close();
}
}
else
{
MessageBox.Show("Please Fill Data");
}

OriginalGriff25-Mar-22 23:55

25-Mar-22 23:55

Quote:
My insert code is not working fine, bcz if i click radionbutton2 and checkbox 2 means it was inserting data automatically radionbutton1 and checkbox1 only, actually if which textbox is selected that data should enter null value radionbutton data should not saved in db

The question is meaningless, you still haven't learned how to use a debugger, and you are still trying to get others to fix problems instead of thinking about what is actually going on.

what have you tried to work out what the problem might be, given that we can't understand your "explanation" of the problem, run your code, see your inputs, or access your DB?

Richard MacCutchan26-Mar-22 0:19

Richard MacCutchan

26-Mar-22 0:19

And you are still posting a success message even if it fails.

cmd.ExecuteNonQuery();
MessageBox.Show("Record Inserted Successfully");

Luc Pattyn26-Mar-22 9:24

Luc Pattyn

26-Mar-22 9:24

Optimism is a moral duty...

Big Grin | :-D

Luc Pattyn [My Articles]
The Windows 11 "taskbar" is disgusting. It should be at the left of the screen, with real icons, with text, progress, etc. They downgraded my developer PC to a bloody iPhone.

Craig Robbins26-Mar-22 3:36

Craig Robbins

26-Mar-22 3:36

I'm sorry but i don't understand your question. One thought I have - are you trying to do an 'exclusive or'? In other words, are you trying to see if button 1 is selected, or button 2 is selected, but not both at the same time?

As others have pointed out a few different times in response to your questions - you cannot assume a SQL command is successful just because control moves to the next statement. You need to check to see if you were able to perform the SQL statement. You may lose your connection, you may not be authorized to the database, the update may have failed to run. There are ways to see if the SQL statement worked before you proceed to posting a 'success' message.

N Mohamed rafi26-Mar-22 5:16

N Mohamed rafi

26-Mar-22 5:16

yes sir need to select any one at a time. and i am using mysql not sql