I am trying to dynamically create a StringBuilder array in C# and I haven't had much luck.
I want to add information to a StringBuilder (sb) based off of a given client digit that will change dynamically depending on how many clients I might have. I might have 2 or I might have 20. The sb will be used to build a report based per client later in my program.
For example I have the following 3 clients:
Client A = 0
Client B = 1
Client C = 2
If Client A is reporting he has 8 apples I want to add the string "8 apples" to sb[0].
If Client B is reporting he has 3 oranges I want to add the string "3 oranges" to sb[1].
The above is just a simple example of the idea I am trying to accomplish. In reality I am going to be adding a lot of information to the sb.
I have tried the following without much luck getting them to work they way I expected or wanted.
StringBuilder[] sbFileError = new StringBuilder[clientCount];
List<StringBuilder> sbFileError = new List<StringBuilder>();
Any thoughts? Is it possible to create a StringBuilder array?
Thanks!
You've created the containers above, but you need to fill them with something. For example:
StringBuilder[] sbFileError = new StringBuilder[clientCount];
for (int ix = 0; ix < clientCount; ++ix)
sbFileError[ix] = new StringBuilder();
Or
List<StringBuilder> sbFileError = new List<StringBuilder>();
for (int ix = 0; ix < clientCount; ++ix)
sbFileError.Add(new StringBuilder());
Creating the array is the first step, but this only creates places to store StringBuilders. You haven't actually instantiated any StringBuilders at this point. You'll need to do something like this....
StringBuilder[] sbFileError = new StringBuilder[clientCount];
for (int i = 0; i < sbFileError.Length; i++)
sbFileError[i] = new StringBuilder();
I think you are missing instantiation of array elements.
This code works.
int clientCount = 3;
StringBuilder[] sbFileError = new StringBuilder[clientCount];
for(int i=0; i<clientCount; i++)
{
sbFileError[i] = new StringBuilder();
}
sbFileError[1].Append("Hello World!");
List<StringBuilder> sbFileError = new List<StringBuilder>();
Looks OK, but you have to fill it:
for (int i = 0; i < numClients; i++)
sbFileError.Add(new StringBuilder());
You could also get fancy:
var items = Enumerable.Range(0, clientCount)
.Select(i => new StringBuilder());
var list = new List<StringBuilder>(items);
or shorten it to:
var list = Enumerable.Range(0, clientCount)
.Select(i => new StringBuilder())
.ToList();
Just another egg in the basket.
Related
I have a C# console window program and I am trying to sort "File3" (contains numbers) in ascending and output lines from 3 text files.
So the outcome looks something like this:
===========================================================================
field1.....................field2.....................field3
===========================================================================
[FILE1_LINE1]..............[FILE2_LINE1]..............[FILE3_LINE1]
[FILE1_LINE2]..............[FILE2_LINE2]..............[FILE3_LINE2]
[FILE1_LINE3]..............[FILE2_LINE3]..............[FILE3_LINE3]
and so on...
At the moment, it kinda works I think but it duplicates the first two lines it seems. Could someone give an example of better coding please?
Here is the code that I have atm:
string[] File1 = System.IO.File.ReadAllLines(#"FILE1.txt");
string[] File2 = System.IO.File.ReadAllLines(#"FILE2.txt");
string[] File3 = System.IO.File.ReadAllLines(#"FILE3.txt");
decimal[] File3_1 = new decimal[File3.Length];
for(int i=0; i<File3.Length; i++)
{
File3_1[i] = decimal.Parse(File3[i]);
}
decimal[] File3_2 = new decimal[File3.Length];
for(int i=0; i<File3.Length; i++)
{
File3_2[i] = decimal.Parse(File3[i]);
}
decimal number = 0;
for (double i = 0.00; i < File3_1.Length; i++)
{
for (int sort = 0; sort < File3_1.Length - 1; sort++)
{
if (File3_1[sort] > File3_1[sort + 1])
{
number = File3_1[sort + 1];
File3_1[sort + 1] = File3_1[sort];
File3_1[sort] = number;
}
}
}
if (SortChoice2 == 1)
{
for (int y = 0; y < File3_2.Length; y++)
{
for (int s = 0; s < File3_2.Length; s++)
{
if (File3_1[y] == File3_2[s])
{
Console.WriteLine(File1[s] + File2[s] + File3_1[y]);
}
}
}
}
Just for more info, most of this code was used for another program and worked but in my new program, this doesn't as I've said above - ("it repeats a couple of lines for some reason"). I'm kinda an amateur/ rookie at C# so I only get stuff like this to work with examples.
Thanks in advance :)
Ok, if I understand correctly, what you are trying to do is read the lines from 3 different files, each of them representing a different "field" in a table. You then want to sort this table based on the value of one of the field (in you code, this seems to be the field which values are contained in File3. Well, if I got that right, here's what I suggest you do:
// Read data from files
List<string> inputFileNames = new List<string> {"File1.txt", "File2.txt", "File3.txt"};
decimal[][] fieldValues = new decimal[inputFileNames.Count][];
for (int i = 0; i < inputFileNames.Count; i++)
{
string currentInputfileName = inputFileNames[i];
string[] currentInputFileLines = File.ReadAllLines(currentInputfileName);
fieldValues[i] = new decimal[currentInputFileLines.Length];
for (int j = 0; j < currentInputFileLines.Length; j++)
{
fieldValues[i][j] = decimal.Parse(currentInputFileLines[j]);
}
}
// Create table
DataTable table = new DataTable();
DataColumn field1Column = table.Columns.Add("field1", typeof (decimal));
DataColumn field2Column = table.Columns.Add("field2", typeof (decimal));
DataColumn field3Column = table.Columns.Add("field3", typeof (decimal));
for (int i = 0; i < fieldValues[0].Length; i++)
{
var newTableRow = table.NewRow();
newTableRow[field1Column.ColumnName] = fieldValues[0][i];
newTableRow[field2Column.ColumnName] = fieldValues[1][i];
newTableRow[field3Column.ColumnName] = fieldValues[2][i];
table.Rows.Add(newTableRow);
}
// Sorting
table.DefaultView.Sort = field1Column.ColumnName;
// Output
foreach (DataRow row in table.DefaultView.ToTable().Rows)
{
foreach (var item in row.ItemArray)
{
Console.Write(item + " ");
}
Console.WriteLine();
}
Now, I tried to keep the code above as LINQ free as I could, since you do not seem to be using it in your example, and therefore might not know about it. That being said, while there is a thousand way to do I/O in C#, LINQ would help you a lot in this instance (and in pretty much any other situation really), so I suggest you look it up if you don't know about it already.
Also, the DataTable option I proposed is just to provide a way for you to visualize and organize the data in a more efficient way. That being said, you are in no way obliged to use a DataTable: you could stay with a more direct approach and use more common data structures (such as lists, arrays or even dictionaries if you know what they are) to store the data, depending on your needs. It's just that with a DataTable, you don't, for example, need to do the sorting yourself, or deal with columns indexed only by integers. With time, you'll come to learn about the myriad of useful data structure and native functionalities the C# language offers you and how they can save you doing the work yourself in a lot of cases.
I have a comma delimited text file that contains 20 digits separated by commas. These numbers represent earned points and possible points for ten different assignments. We're to use these to calculate a final score for the course.
Normally, I'd iterate through the numbers, creating two sums, divide and be done with it. However, our assignment dictates that we load the list of numbers into two arrays.
so this:
10,10,20,20,30,35,40,50,45,50,45,50,50,50,20,20,45,90,85,85
becomes this:
int[10] earned = {10,20,30,40,45,50,20,45,85};
int[10] possible = {10,20,35,50,50,50,20,90,85};
Right now, I'm using
for (x=0;x<10;x++)
{
earned[x] = scores[x*2]
poss [x] = scores[(x*2)+1]
}
which gives me the results I want, but seems excessively clunky.
Is there a better way?
The following should split each alternating item the list into the other two lists.
int[20] scores = {10,10,20,20,30,35,40,50,45,50,45,50,50,50,20,20,45,90,85,85};
int[10] earned;
int[10] possible;
int a = 0;
for(int x=0; x<10; x++)
{
earned[x] = scores[a++];
possible[x] = scores[a++];
}
You can use LINQ here:
var arrays = csv.Split(',')
.Select((v, index) => new {Value = int.Parse(v), Index = index})
.GroupBy(g => g.Index % 2,
g => g.Value,
(key, values) => values.ToArray())
.ToList();
and then
var earned = arrays[0];
var possible = arrays[1];
Get rid of the "magic" multiplications and illegible array index computations.
var earned = new List<int>();
var possible = new List<int>();
for (x=0; x<scores.Length; x += 2)
{
earned.Add(scores[x + 0]);
possible.Add(scores[x + 1]);
}
This has very little that would need a text comment. This is the gold standard for self-documenting code.
I initially thought the question was a C question because of all the incomprehensible indexing. It looked like pointer magic. It was too clever.
In my codebases I usually have an AsChunked extension available that splits a list into chunks of the given size.
var earned = new List<int>();
var possible = new List<int>();
foreach (var pair in scores.AsChunked(2)) {
earned.Add(pair[0]);
possible.Add(pair[1]);
}
Now the meaning of the code is apparent. The magic is gone.
Even shorter:
var pairs = scores.AsChunked(2);
var earned = pairs.Select(x => x[0]).ToArray();
var possible = pairs.Select(x => x[1]).ToArray();
I suppose you could do it like this:
int[] earned = new int[10];
int[] possible = new int[10];
int resultIndex = 0;
for (int i = 0; i < scores.Count; i = i + 2)
{
earned[resultIndex] = scores[i];
possible[resultIndex] = scores[i + 1];
resultIndex++;
}
You would have to be sure that an equal number of values are stored in scores.
I would leave your code as is. You are technically expressing very directly what your intent is, every 2nd element goes into each array.
The only way to improve that solution is to comment why you are multiplying. But I would expect someone to quickly recognize the trick, or easily reproduce what it is doing. Here is an excessive example of how to comment it. I wouldn't recommend using this directly.
for (x=0;x<10;x++)
{
//scores contains the elements inline one after the other
earned[x] = scores[x*2] //Get the even elements into earned
poss [x] = scores[(x*2)+1] //And the odd into poss
}
However if you really don't like the multiplication, you can track the scores index separately.
int i = 0;
for (int x = 0; x < 10; x++)
{
earned[x] = scores[i++];
poss [x] = scores[i++];
}
But I would probably prefer your version since it does not depend on the order of the operations.
var res = grades.Select((x, i) => new {x,i}).ToLookup(y=>y.i%2, y=>y.x)
int[] earned = res[0].ToArray();
int[] possible = res[1].ToArray();
This will group all grades into two buckets based on index, then you can just do ToArray if you need result in array form.
here is an example of my comment so you do not need to change the code regardless of the list size:
ArrayList Test = new ArrayList { "10,10,20,20,30,35,40,50,45,50,45,50,50,50,20,20,45,90,85,85" };
int[] earned = new int[Test.Count / 2];
int[] Score = new int[Test.Count / 2];
int Counter = 1; // start at one so earned is the first array entered in to
foreach (string TestRow in Test)
{
if (Counter % 2 != 0) // is the counter even
{
int nextNumber = 0;
for (int i = 0; i < Score.Length; i++) // this gets the posistion for the next array entry
{
if (String.IsNullOrEmpty(Convert.ToString(Score[i])))
{
nextNumber = i;
break;
}
}
Score[nextNumber] = Convert.ToInt32(TestRow);
}
else
{
int nextNumber = 0;
for (int i = 0; i < earned.Length; i++) // this gets the posistion for the next array entry
{
if (String.IsNullOrEmpty(Convert.ToString(earned[i])))
{
nextNumber = i;
break;
}
}
earned[nextNumber] = Convert.ToInt32(TestRow);
}
Counter++
}
I am creating an application in window application using c#. I have a string array,and its value will be updated in each timer tick event. later on ,i have to convert this array into object array. I know, if we are modifying string many times,it can be time consuming to create new string objects.so i want to use stringBuilder.
let say, in timer tick event:
for (int i = 0; i < 10; i++)
{
n[i] = i.ToString();
}
where n is the string array and i want to use stringbuilder instead of array.
is it possible? how do i do this? how do i convert stringBuilder type to object type?
You do not need a StringBuilder here. A StringBuilder is only called for when processing (usually: concatenating) a single string many times. You have many small and unrelated strings.
What you probably want is to replace the array string[] with a List<string>.
You can keep your array of strings and use a StringBuilder in the loop.
var myValues = new String[100];
void tick() {
var sb = new StringBuilder();
for (int i = 0; i < 10; i++){
sb.append(i.ToString());
}
myValues.add(sb.ToString());
}
This adds all values in the range of 0 to 10 to one string. I don't know why you'd need this, so if you want to do something different you should clarify.
You can do something like this
StringBuilder obj=new StringBuilder();
for (int i = 0; i < 10; i++)
{
obj.append(i.ToString());
}
Here is another approach that does not need to use an array or StringBuilder and which should be efficient enough if the sequence is not too large:
string nums = String.Join("", Enumerable.Range(0, 10));
However, string.Join is really efficient if the input is already an array. In this case it might really be more efficient to use a StringBuilder:
string nums = Enumerable.Range(0, 10)
.Aggregate(new StringBuilder(), (a, b) => a.Append(b))
.ToString();
I would suggest you to use code something like :
class Program
{
static void Main(string[] args)
{
var dic = new Dictionary<int, StringBuilder>();
//Initialize dictionary
for (int i = 0; i < 10; i++)
{
dic.Add(i, new StringBuilder());
}
TimerElapsed(dic);
TimerElapsed(dic);
Process(dic.Values.ToArray());
}
public static void Process(object[] objects)
{
//Do your processing
}
public static void TimerElapsed(IDictionary<int, StringBuilder> dic)
{
for (int i = 0; i < 10; i++)
{
dic[i].Append(i.ToString());
}
}
}
Such code will give you benefits of collection and flexibility (for eg: you could convert to array easily)
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().
var examples = new double[1000][][];
for (int i = 0; i < 1000; i++)
{
examples[i]= new double[2][]; //the Set
examples[i][0] = new double[] { x(i), y(i) }; //the Inputs
examples[i][1] = new double[] { Math.Sin(x(i) * y(i)), Math.Sin(x(i) / y(i)) }; //the Target
}
x(i) means x depend on i
And I need to collect the inputs like that examples[][0] = new double[1000][]
because It will consume more memory to create a new array like that
for (int i = 0; i < 1000; i++)
{
input[i][0]=x(i);
input[i][1]=y(i);
}
My first thought would be to reconsider the design decision that ended up with a [1000][2][2] array which you want to pull a flattened [1000][2] array out of by taking a specific center-array value...
As far as accessing it without re-allocating memory, you're not going to get it as an array without using more memory sorry, but what you could do is get an IEnumerable<double[]> which may suffice depending on your purposes by using yield (Which will make it evaluate each result individually as you enumerate over it).
EG:
public IEnumerable<double[]> GetResults()
{
for (int i = 0; i < 1000; x++)
{
yield return examples[i][0];
}
}
How useful that is will depend on how you plan to use the results, but you won't get a new array without using more memory.