We Keep Coding

How to convert a string array to an int array

I have been trying to make a program in which, I add data of numbers but in texts, that these are added to a listbox and later make the sum of said values, only that they have explained to me that once the data has been added, now I must do a for loop to go through each data of the first array and thus be able to convert each one of them to a numeric value. Only when doing the conversion on the add button, it tells me that it is not in the correct format.
I declared the array in the public partial class like this: string [] array;
private void bt_capturar_Click(object sender, EventArgs e)
{
string datos = txb_numeros.Text;
arreglo = datos.Split(',');
lbx_elementos.Items.Clear();
foreach (string elementos in arreglo)
{
lbx_elementos.Items.Add(elementos);
}
}
private void bt_sumar_Click(object sender, EventArgs e)
{
int suma = 0;
for (int x = 0; x < arreglo.Length; x++)
{
int numero;
numero = int.Parse(arreglo[x]);
suma = suma + numero;
}
MessageBox.Show("La suma es igual a " + suma.ToString());
}

Often we query array with a help of Linq (note, that we use int.TryParse since some items can not represent any integer value)
using System.Linq;
...
private void bt_sumar_Click(object sender, EventArgs e)
{
int suma = arreglo.Sum(item => int.TryParse(item, out int v) ? v : 0);
MessageBox.Show($"La suma es igual a {suma}");
}
However, you can implement a simple loop:
private void bt_sumar_Click(object sender, EventArgs e)
{
int suma = 0;
foreach (string item in arreglo)
suma += int.TryParse(item, out int v) ? v : 0;
MessageBox.Show($"La suma es igual a {suma}");
}

Use Int32.TryParse instead
int numero;
bool success = Int32.TryParse(arreglo[x], out numero);
suma += success ? numero : 0;

If I understand correctly, you want to already validate the input or convert it in bt_capturar_Click?
In that case you can do the following:
private void bt_capturar_Click(object sender, EventArgs e)
{
string datos = txb_numeros.Text;
arreglo = datos
.Split(',')
.Select(Int32.Parse)
.ToArray();
// Or ignore invalid values:
//arreglo = datos
// .Split(',')
// .Select(s => Int32.TryParse(s, out int n) ? n : (int?)null)
// .Where(n => n != null)
// .ToArray();
lbx_elementos.Items.Clear();
foreach (string elementos in arreglo)
{
lbx_elementos.Items.Add(elementos.ToString()); // Maybe use AddRange?
}
}
private void bt_sumar_Click(object sender, EventArgs e)
{
MessageBox.Show("La suma es igual a " + arreglo.Sum());
}
}

Using the following simple code, you will resolve your problem easily.
string strInput = "1,2,3,4,5";
string[] arrInput = strInput.Split(',');
// convert a string array to an int array
int[] arrResult = Array.ConvertAll(arrInput, s => int.TryParse(s, out int t) ? t : 0);
// sum up an array of integers
int nSum = arrResult.Sum();
References:
Array.ConvertAll, int.TryParse, Enumerable.Sum

find the first element of an array that is not consecutive using web forms

E.g. If we have an array [1,2,3,4,6,7,8] then 1 then 2 then 3 then 4 are all consecutive but 6 is not, so that's the first non-consecutive number.
If the whole array is consecutive then return null .
The array will always have at least 2 elements 1 and all elements will be numbers. The numbers will also all be unique and in ascending order. The numbers could be positive or negative and the first non-consecutive could be either too. please help me finish this code i am new in programming. My code:
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace _2katas
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
var input = this.txtInput.Text;
var numarray = input.Split(',');
int firstValue = Convert.ToInt32(numarray[0]);
for (var i = 0; i < numarray.Length; i++)
{
if (Convert.ToInt32(numarray[i]) - i != firstValue)
{
lblPrint.Text = "";
}
else
{
lblPrint.Text = "";
}
if (this.rdbConsecutive.Checked == true)
{
lblKataRunning.Text = "Consecutive";
}
else if (this.rdbStripCleaning.Checked == true)
{
lblKataRunning.Text = "Strip Cleaning";
}
}
}
}
}

Let's extract a method:
Find the first element of an array that is not consecutive ...
If the whole array is consecutive then return null
We can implement it like this:
private static string FirstInconsecutive(string data) {
var array = data.Split(',');
if (array.Length <= 0)
return null; //TODO: what shall we return on empty array?
if (!int.TryParse(array[0], out int delta))
return array[0];
for (int i = 1; i < array.Length; ++i)
if (!int.TryParse(array[i], out int value) || value - i != delta)
return array[i];
return null;
}
Usage:
string result = FirstInconsecutive(txtInput.Text);
Please note int.TryParse which helps to return the right answer "ABC" on an input like "1, 2, 3, ABC, 4, 6, 7, 8" (user input txtInput.Text can contain any string)

A linq solution just for the fun of it:
static int? FindFirstNonConsecutive(IEnumerable<int> arr)
{
var nonConsecutiveInfo =
arr.Select((i, index) => new {Index = index, Delta = i - index})
.FirstOrDefault(t => t.Delta != arr.First());
return nonConsecutiveInfo?.Delta + nonConsecutiveInfo?.Index;
}
Note that this will only work finding non consecutive numbers in ascending order as per requirements.

Two numbers are not consecutive if the left ones + 1 <> the right one.
Check with something like this, note that you have to change your boundary checks:
for (var i = 0; i < numarray.Length - 1; i++)
{
if (Convert.ToInt32(numarray[i]) + 1 != Convert.ToInt32(numarray[i+1]))

Update your condition as below for loop and it will work. I would suggest you to have separate function so that it could be reusable if needed elsewhere in code.
Here start your loop from i = 1 and compare numarray[i-1] + 1 != numarray[i] values.
You can convert your sting[] to int[] with var numarray = input.Split(',').Select(x => Convert.ToInt32(x)).ToArray(); and use it with IsConsecutive(numarray) as per button1_Click code.
You can get first non-consecutive value with minor modification in return type and return statement as shown in GetFirstNonConsecutiveValue().
public bool IsConsecutive(int[] numarray)
{
for (int i = 1; i < numarray.Length; i++)
{
if (numarray[i-1] + 1 != numarray[i])
{
return false;
}
}
return true;
}
public int? GetFirstNonConsecutiveValue(int[] numarray)
{
for (int i = 1; i < numarray.Length; i++)
{
if (numarray[i-1] + 1 != numarray[i])
{
return numarray[i];
}
}
return null;
}
private void button1_Click(object sender, EventArgs e)
{
var input = this.txtInput.Text;
var numarray = input.Split(',').Select(x => Convert.ToInt32(x)).ToArray();
var nonConsecutiveValue = GetFirstNonConsecutiveValue(numarray);
if (nonConsecutiveValue != null)
{
// nonConsecutiveValue is first non consecutive value.
}
else
{
// sequence is consecutive.
}
}

One way to go.
string rawData = "1,2,3,4,6,7,8,9";
IEnumerable<int> data = rawData.Split(',').Select(v => Convert.ToInt32(v));
IEnumerable<int> all = Enumerable.Range(data.Min(), data.Max() - data.Min() + 1);
IEnumerable<int> diff = all.Except(data);
if (diff.Count() == 0)
{
return null;
}
return data.ElementAt(all.ToList().IndexOf(diff.First()))
NB Not thoroughly tested.
Just test diff for being empty to get the numbers are consecutive

C# - How to add a number to a already existing number?

Basically my question is how i add to a number like a calculator does for example? My code currently looks like this but it does a add operation instead of adding the number behind the existing number.
private void button1_Click(object sender, RoutedEventArgs e)
{
value1 = value1 + 1;
output = value1;
textresult.Text = output.ToString();
if the user presses the button twice it would be 2. I want it to be 11. How do i do this?

You should use string variable instead int variable
int a = 1;
int b = 1;
int c = a+b;
The result of c is 2
string a = "1";
string b = "1";
string c = a+b;
If you use string it will be "11"

Stuck with two dimensional array

I'm trying to create a booking service and I've been stuck on this part for many hours and I just can't figure out what I'm doing wrong.
So I've got a Two Dimensional array and when trying to print out some stuff when testing and trying to figure out what's wrong, all I get is System.String[] which doesn't really make me any wiser. I want to be able to access the details in i.e. m_nameMatrix[0,0] to check whether the seat is reserved or not.
Here's a snippet from my form code:
private void UpdateGUI(string customerName, double price)
{
string selectedItem = cmdDisplayOptions.Items[cmdDisplayOptions.SelectedIndex].ToString();
rbtnReserve.Checked = true;
lstSeats.Items.Clear();
lstSeats.Items.AddRange(m_seatMngr.GetSeatInfoStrings(selectedItem));
}
And here are two methods from my 2nd class:
public string[] GetSeatInfoStrings(string selectedItem)
{
int count = GetNumOfSeats(selectedItem);
if (count <= 0)
{
return new string[0];
}
string[] strSeatInfoStrings = new string[count];
for (int index = 0; index <= count; index++)
{
strSeatInfoStrings[index] = GetSeatInfoAt(index);
}
return strSeatInfoStrings;
}
public string GetSeatInfoAt(int index)
{
int row = (int)Math.Floor((double)(index / m_totNumOfCols));
int col = index % m_totNumOfCols;
string seatInfo = m_nameMatrix.GetValue(row, col).ToString();
return seatInfo;
}
I'm not actually getting an exception so it might be my logical thinking that's been taking a hit due to hours and hours of trying to figure it out.
EDIT:
public void ReserveSeat(string name, double price, int index)
{
int row = (int)Math.Floor((double)(index / m_totNumOfCols));
int col = index % m_totNumOfCols;
string reserved = string.Format("{0,3} {1,3} {2, 8} {3, 8} {4,22:f2}",
row + 1, col + 1, "Reserved", name, price);
m_nameMatrix[row, col] = reserved;
}

This line:
for (int index = 0; index <= count; index++)
should be:
for (int index = 0; index < count; index++)
Why? Lets say I have an array with 2 objects in it. count would be 2. However, the indexes are 0 and 1. So you have to use a less than operator.

If you're getting "System.String[]" in your messagebox, it's because you're trying to print a string[] directly, rather than the various strings it contains:
string[] data = GetSeatInfoStrings("foo");
MessageBox.Show(data);
Instead, you need to show the contents of data:
string[] data = GetSeatInfoStrings("foo");
MessageBox.Show(string.Join("\n", data));
See here for the documentation.

Suppose you had a method called ReturnArray():
class Class2
{
public string[] ReturnArray()
{
string[] str = new string[] { "hello", "hi" };
return str;
}
}
If you called ReturnArray in your main class like this:
Class2 class2 = new Class2();
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show(class2.ReturnArray());
}
it will return System.String[] because MessageBox.Show(...) takes a string as an argument, in this case.
So you'll also get the same result by using MessageBox.Show(class2.ReturnArray().ToString());
Instead, you may want to do something like this:
Class2 class2 = new Class2();
private void button1_Click(object sender, EventArgs e)
{
string[] strArray = class2.ReturnArray();
listBox1.Items.AddRange(strArray);
}

"Input string was not in a correct format." for Convert() method

i have debugged my code (below) and found out the problem is the Convert() method that converts the text from the textbox. but how i fix this problem?
i have a example of similar problem here.
code:
//METHODS
static string RollDice (int dice)
{
Random roll = new Random();
int rollOutput = roll.Next(1, dice);
//NOTE: VERY IMPORTANT! EVERY TIME THE INPUT GOES INTO THIS
//METHOD REMEMBER TO INCREACE IT BY ONE!
//AND NEVER LET THE USER TO ROLL TO DICE QUICKLY ONE AFTER ANOTHER!
string rollResult = rollOutput.ToString();
return rollResult;
}
static void TwiceD20(int bonus, bool advantage)
{
string firstRollString = RollDice(21) + bonus;
string secondRollString = RollDice(21) + bonus;
int firstRoll = Convert.ToInt32(firstRollString);
int secondRoll = Convert.ToInt32(secondRollString);
switch(advantage)
{
case true:
if (firstRoll >= secondRoll)
{
MessageBox.Show(firstRollString);
}
else
{
MessageBox.Show(secondRollString);
}
break;
case false:
if (firstRoll <= secondRoll)
{
MessageBox.Show(firstRollString);
}
else
{
MessageBox.Show(secondRollString);
}
break;
}
}
//BUTTONS
private void btn1d20_Click(object sender, EventArgs e)
{
MessageBox.Show("Roll Result: " + RollDice(21));
}
private void btnAdv_Click(object sender, EventArgs e)
{
TwiceD20(Convert.ToInt32(textBox1d20.Text), true);
}
private void btnDisAdv_Click(object sender, EventArgs e)
{
TwiceD20(Convert.ToInt32(textBox1d20.Text), false);
}

You have added a non-int into the string. So naturally you cannot convert that to an int because the string is not just an int anymmore.
string firstRollString = RollDice(21) + bonus; // This won't convert back to an int
string secondRollString = RollDice(21) + bonus; // This won't convert back to an int
int firstRoll = Convert.ToInt32(firstRollString);
int secondRoll = Convert.ToInt32(secondRollString);
Adding bonus to the string result of RollDice is simply appending the string "True" or "False" to the result of RollDice. I suspect that you think it is adding a numerical 0 or 1.
I would do as the comments suggest and have RollDice return a number. Then you can turn it into a string and manipulate it later as you see fit.
Or, if you don't want to return anything, just make a quick change to the order of operations.
int firstRoll = Convert.ToInt32(RollDice(21));
int secondRoll = Convert.ToInt32(RollDice(21));
string firstRollString = firstRoll + bonus;
string secondRollString = secondRoll + bonus;
But, not knowing for sure what you intend for your code to do, even that may not work for you.