Im doing this:
string[,] string1 = {{"one", "0"},{"Two", "5"},{"Three","1"}};
int b = 0;
for(int i = 0; i <= string1.Length; i++)
{
b = int.Parse(string1[i, 1]); // Error occurs here
}
Im getting an error saying that "index extent the limits of the array" (or something like that, the error is in danish).
There are two problems:
string1.Length will return 6, as that's the total length of the array
You're using <= for the comparison, so it would actually try to iterate 7 times.
Your for loop should be:
for (int i = 0; i < string1.GetLength(0); i++)
The call to GetLength(0) here will return 3, as the size of the "first" dimension. A call to GetLength(1) return 2, as the second dimension is of size 2. (You don't need that though, as you're basically hard-coding the knowledge that you want the second "column" of each "row".)
See the docs for Array.GetLength() for more details.
Your array bounds are incorrect in the loop:
for(int i = 0; i <= string1.Length; i++)
should read:
for(int i = 0; i < string1.GetLength(0); i++)
Two things were wrong: <= versus < meant you were going one item too far, and .Length returns the total length of the array (6) versus GetLength(0) which returns the length of the first dimension (3).
You already have the right answer, I'll update mine just to correct it. To right iteration should be
for (int i = 0; i < string1.GetLength(0); i++)
{
b = int.Parse(string1[i, 1]);
}
Because i stands for the length of the first dimension, and the fixed 1 will return the number, that is the second element.
I'm sorry for the wrong answer I gave first.
Change i <= string1.Length to i < string1.Length.
change to
for(int i = 0; i <= string1.GetLength(0); i++)
{
b = Int32.Parse(string1[i][0]);
}
Your code is refering at index 1 rather than 0 which causes exception known as Array out of bound
Try this:
for(int i = 0; i < string1.GetLength(0) ; i++)
{
b = int.parse(string1[i, 0]); // Error occurs here
}
Array.GetLength Method
Gets a 32-bit integer that represents the number of elements in the specified dimension of the Array.
Also worth mentioning that int.Parse may throw a FormatException, consider int.TryParse.
Related
Well I'm trying to write a program in which if you add for example 3 integers in the array, let's say 3 2 1, it will add them again after it so it becomes 321 321.
Here is the code I need to fix. And sorry for the stupid question I am a beginner with arrays.
I get this error
Index was outside the bounds of the array
My code:
using System;
public class Program
{
public static void Main()
{
int arraylength = int.Parse(Console.ReadLine());
int[] array = new int[arraylength];
for (int i = 0; i < arraylength + 1 / 2; i++)
{
int typed = int.Parse(Console.ReadLine());
array[i] = typed;
if (i == arraylength / 2)
{
for (int a = arraylength + 1 / 2; a < arraylength + 1; a++)
{
array[a] = typed;
}
}
}
}
}
Array indices in C# start at 0 and end at length - 1. You need to remove the + 1 from each of your for loop conditions:
for (int i = 0; i < arraylenght / 2; i++)
and
for (int a = (arraylenght + 1) / 2; a < arraylenght; a++)
I also suggest that you change arraylenght to arraylength. Since you probably autocompleted this every time you used it, the misspelling occurs consistently throughout your code and the compiler is satisfied. However, misspellings make it difficult for humans to read your code.
p.s. Your code doesn't do what you think it does. I suggest you step away from the computer for a moment and write in words what you are trying to accomplish. Describe each step of your solution in as much detail as you can. Then look at how your words match with the code you wrote. You will probably find that you do not need nested loops.
TLDR: Codility "Challenge" - my results: Where is the error?
Short Description (Full Description): Given an Array, split the array into two (Upper and lower parts) and give the minimum difference between two possible parts in absolute value.
My thought process is:
create an "Upper" and "Lower" bucket for sums.
In one pass of the array, we get a sum for the "Upper" bucket.
Then, one array value at a time, move the numbers into lower (Upper-n, Lower+n).
At each step, get the difference (Abs(Upper-lower))
Monitor lowest "Minimum"
Submitted Code:
public int solution(int[] A)
{
// Quick results:
if (A == null) return -1;
if (A.Length == 0) return -1; // Can't split
if (A.Length == 1) return -1; // Can't split
if (A.Length == 2) return Math.Abs(A[0] - A[1]); // Only one way to split
// Hold above/below/result...
long lower = 0;
long upper = 0;
var min = long.MaxValue;
// Pass#1: Sum All to get "Upper"
for (long i = 0; i < A.Length; i++) upper += A[i];
// Pass#2:
// foreach in array
// ... Shift number from upper to lower
// ... Calculate new difference/minimum
for (var i = 0; i < A.Length; i++)
{
lower += A[i];
upper -= A[i];
var diff = Math.Abs(upper - lower);
min = Math.Min(min, diff);
if (diff == 0) return 0;
}
return (int) min;
}
Out of 13 test cases, the only one that Codility fails me on is: "Small Numbers". it says "Wrong answer, expected 20 got 0". It doesn't show the test data it uses, so I'm left guessing as to "Why".
Where is my error? I think I've stared at it too much, but I can't seem to figure out what case would "break" my function.
Edit: Fixed translation. Submitted code to Codility uses a Foreach, and the code I have here is a For. Corrected the variables in the loop.
The problem is that you didn't take into account one of the rules: 0 < P < N.
Your second loop is assuming 0 < P <= N.
Assume this input:
10, 10, -20
Your code would return 0 but 40 would be correct.
Fix:
Change your second loop header to
for (var i = 0; i < A.Length - 1; i++)
Proof
I need to use a data structure that would keep the latest X elements of a list. A colleague gave me this solution:
int start = 0;
const int latestElementsToKeep = 20;
int[] numbers = new int[latestElementsToKeep];
for (int i = 0; i < 30; i++)
{
numbers[start] = i;
if (start < numbers.Length - 1)
{
start++;
}
else
{
start = 0;
}
}
So after this is run, the numbers array has numbers 19-29 (the latest 20 numbers).
That's nice, but difficult to use this in the real world. Is there an easier way to do this?
This seems like a pretty standard Circular Buffer. My only suggestion would be to create a class for it or download one of the libraries available. There seem to be a few promising looking ones near the top of the Google results.
Easier way to do this:
int[] numbers = new int[latestElementsToKeep];
for (int i = 0; i < 30; i++)
numbers[i % latestElementsToKeep] = i;
Modulus operator returns the reminder of dividing i by latestElementsToKeep. When i reaches latestElementsToKeep, you will start from the beginning.
For a range of numbers, you can use:
int keep = 20;
int lastItem = 29;
int[] numbers = Enumerable.Range(lastItem - keep, keep).ToArray();
To get the last items from any collection (where you can get the size), you can use:
int keep = 20;
someType[] items = someCollection.Skip(someCollection.Count() - keep).ToArray();
i can't find any mistakes in my code.
here i'm trying to pick all numbers from the string:
(just to simplify the example,, i want to pick numbers that will satisfy some condition)
i use Queue cause i don't want to deal with array's indexes.
Console.Write("enter string: ");
string s = Console.ReadLine();
char[] array = s.ToCharArray();
Queue<char> q = new Queue<char>();
for (int i = 0; i < array.Length; i++)
{
q.Enqueue(array[i]);
}
char[] new_array = new char[q.Count];
for (int i = 0; i < q.Count; i++)
{
new_array[i] = q.Dequeue();
}
Console.WriteLine(new String(new_array));
Input string: 123456
And the output is a little weird:
123
another input: 123
output: 12
of course i made some mistake) but everything seems to be OK
Thank YOU in advance
The problem is the second loop:
for (int i = 0; i < q.Count; i++)
{
new_array[i] = q.Dequeue();
}
As q.Count decrements on every loop iteration, and i increases on every interation, you get only half of the elements.
try something like:
for (int i = 0; q.Count > 0; i++)
{
new_array[i] = q.Dequeue();
}
also consider: Queue.toArray
I would suggest using List<char> instead of Queue<char> and char[]. There's nothing here that particularly needs a queue, and it would avoid the problem that Rudolf pointed out, and a List is much easier to work with than an array. You can also use foreach instead of a for loop, and avoid the intermediate step.
Console.Write("enter string: ");
string s = Console.ReadLine();
List<char> new_array = new List<char>();
foreach(char c in s.ToCharArray())
{
new_array.Add(c);
}
Console.WriteLine(new String(new_array.ToArray()));
As the reason for your error is already stated,you can replace your two loops with just two statements
//A version of Queue constructor accepts IEnumerable object.
//you can directly pass the string to the queue constructor.
Queue<char> Que = new Queue<char>("123456");
//Copies the array and the position is preserved
var new_arr= Que.ToArray();
According to MSDN:
Removes and returns the object at the beginning of the Queue.
As you use Dequeue(), the q.Count value changes in each iteration.
So rather than using q.Count in this loop;
for (int i = 0; i < q.Count; i++)
use
int queueSize = q.Count;
for (int i = 0; i < queueSize; i++)
This will keep your looping limit as a constant number rather than calculating it in each iteration to find a different value because of using Dequeue().
For example i have a long[] x
And im doing:
for (int i=0; i<x.length;x--)
{
}
I know that in x for example i have 30 indexs cells.
How can i loop over the cells(indexs) in the x array and find on each cell the length of it and also to get/show the numbers in each cell.
If in x[0] there is 232
And in x[1] there is 21
And so on...
I want to display 232,21,....etc
And then i want to check that if x[i].length is above 0 do...
But there is no x[i].length
So how do i do it ?
I did:
public long GetHistogramMaximum(long[] histogram)
{
long result = 0;
long count = 0;
for (int i = 0; i < histogram.Length; i++)
{
if (histogram[i] > 0)
{
MessageBox.Show(histogram[i].ToString());
break;
}
}
return result;
}
And its working but each time its showing me the number twice why the messagebox is working twice each time ?
If in the first array the number is 33454 then i see the messagebox once and then once again. Whats wrong here ? I want it to show me the number only once each time.
Its like repeating each number and show it once and then once again and only then moving to the next one.
EDIT **
Maybe the problem its showing the number twice each time have something to do with the scroll event im using ?
void trackBar1_Scroll(object sender, EventArgs e)
{
myTrackPanelss1.trackBar1.Minimum = 0;
myTrackPanelss1.trackBar1.Maximum = counter - 1;//list_of_histograms.Count-1;
long[] tt = list_of_histograms[myTrackPanelss1.trackBar1.Value];
histogramControl1.DrawHistogram(tt);
long res = GetTopLumAmount(tt, 1000);
long max = GetHistogramMaximum(tt);
if (res > -1)
label24.Text = (res / 1000.0).ToString();
setpicture(myTrackPanelss1.trackBar1.Value);
this.pictureBox1.Refresh();
}
For some reason its getting to the scroll and do everything here again. Twice in a row.
What can be the problem ?
A long[] basically holds a number of long values. Doing x[i].length is invalid, because a long does not have a property length. What is it that you are trying to achieve?
long[] x = {1,2,3} ;
x.length; //this is valid because you are querying the length / count of the array
x[0].length; //this is invalid because 1 does not have a property length
EDIT
Your loop counter will be the index. So,
for (int i =0; i < x.Length; i++)
{
//check for maximum, when you find it
Console.WriteLine("The maximum value is " + x[i]);
Console.WriteLine("The maximum value is present at index " + i);
}
As Michael says, you can find the length of the array via x.Length. In C#, x.Length (where x is an array) will return a 32-bit integer that represents the total number of elements across all dimensions. You only have a 1D array here, so that should be sufficient for what you're trying to achieve.
If you're also after the value stored in the array, the value is called as:
x[i];
So, in an example:
for ( int i = 0; i < x.Length; i++)
{
Console.WriteLine(x[i]);
}
... would display the value in the array in your console.
Is that what you were asking?
Here is how to do something based on the values in the array.:
for (int i=0; i < x.Length; i++)
{
// print the number to the screen.
Console.WriteLine(x[i]);
if (x[i] > 0) {
// do something else.
}
}
I'm not sure what you meant by x--, but that's probably wrong from your description.
You could cast it to a string and get the length property.
x[i].ToString().Length
Although if you want to check if the length is above zero, then surely just the presence of a value proves this?
Your function has a terrible problem:
public long GetHistogramMaximum(long[] histogram)
{
long result = 0;
long count = 0;
for (int i = 0; i < histogram.Length; i++)
{
if (histogram[i] > 0)
{
MessageBox.Show(histogram[i].ToString());
break;
}
}
return result;
}
This way, you check the values in your array.
When i=0, it checks x[i]. So, 33454 (the value you gave in x[0]) is greater than 0, it shows the number and "break;", so it stops the "for" and do what's next: it returns the result variable that is never modified.
So variables result and count are useless in your code.
Rewrite with something that way for getting the maximum in your array:
public long GetHistogramMaximum(long[] histogram)
{
long result = 0;
for (int i = 0; i < histogram.Length; i++)
{
if (histogram[i] > result)
{
MessageBox.Show(string.Format("{0} is greater than {1}", histogram[i], result);
result = histogram[i];
}
}
return result;
}