How can I add a single Integer to an Integer Array?
if (valuesHigherThanAverage.Length == 0) valuesHigherThanAverage[valuesHigherThanAverage.Length] = arrayGetal;
else valuesHigherThanAverage[valuesHigherThanAverage.Length + 1] = arrayGetal;
I have this code and I have also tried with for or foreach loop but it doesn't worked. And I need to use an INT[] and may not use an List.
You can't add a new item in an array, you have to create a new array with size+1, copy all existing values, and then set the last item value.
An easier way is to use a List<int>, which will automatically resize if you run out of space. Calling the Add method suffices then.
Here a sample of an array resizing algorithm (Array.Resize could automate this, but this is just to show you how it should work):
int[] oldItems = new int[] { 1, 2, 3 };
int[] newItems = new int[oldItems.Length * 2];
for (int i = 0; i < oldItems.Length; i++)
{
newItems[i] = oldItems[i];
}
newItems[oldItems.Length + 1] = 4;
The array is not designed to be extended as new elements are added. You will need to call Array.Resize(Of T) to increase the size but this is will be quite inefficient.
Data types more in line for what you want to do is List<T>.
You cannot change the size of array like valuesHigherThanAverage.Length + 1. It has fixed size. You are crossing the upper bound of the array.
You can create a new Array with the length of the old array + 1.
public static int[] AddIntToArray(int[] sourceArray, int addValue)
{
int[] newArray = new int[sourceArray.Length + 1];
Array.Copy(sourceArray, newArray, sourceArray.Length);
newArray[newArray.Length] = addValue;
return newArray;
}
there are 350 elements in my arraylist , each of it consist of an array of 9 integers i-e Count of each element is 9 . i want to retrievere each of it.
here is what i am trying but giving me
error
"Unable to cast object of type
'System.Collections.Generic.List`1[System.Int32]' to type
'System.Int32[]'."
FileName = "E:\\Normalized_sheet1.txt";
FileStream Fs = File.OpenRead(FileName);
StreamReader SR = new StreamReader(Fs);
while (!SR.EndOfStream)
{
Line = SR.ReadLine().Split('\t'); //make an array of text each time
List<string> arr = new List<string>();
arr.AddRange(Line);
List<int> intList = arr.ConvertAll(s => Int32.Parse(s));
myvalues.Add(intList);
}
SR.Close();
Fs.Close();
for (i = 0; i < Samples; i++)
{
InputParameter=(int[]) myvalues[i]; // Error
}
myvalues.Add(intList.ToArray());
Because you mentioned that you have a list of arrays. If it's a List<int[]> then you can't add lists to it - you can only add arrays. ToArray() returns an array of the items in your list.
If "myvalues" is a List of int[] then your loop should look like this:
for (i = 0; i < Samples; i++)
{
InputParameter= myvalues[i]; //don't need cast.
}
if myvalues is a List of List of int, then your code should be:
for (i = 0; i < Samples; i++)
{
InputParameter= myvalues[i].ToArray();
}
Do not cast, use the appropriate List method:
InputParameter=myvalues[i].ToArray();
I have an Array with Category Names, but now i Need to assign a few Counters to each Category.
Is there a way to expand my 1D-Array to a 2D-Array in C#?
Thanks for helping!
Edit:
PerformanceCounterCategory[] categories;
categories = PerformanceCounterCategory.GetCategories();
string[] categoryNames = new string[categories.Length];
string[] categoryNames_en = new string[categories.Length];
for (int objX = 0; objX < categories.Length; objX++)
{
categoryNames[objX] = categories[objX].CategoryName;
}
Array.Sort(categoryNames);
for (int objX = 0; objX < categories.Length; objX++)
{
Console.WriteLine("{0,4} - {1}", objX + 1, categoryNames[objX]);
}
I have the Array categoryNames with all the Names of the Categories, but in every Category there are a few Counters which i want to assign to their Category somehow...
Unfortunately you can't use Array.Copy since the source and destination array do not have the same dimensions.
Furthermore, you can't expand arrays in C#, since they are initialized with a fixed size.
What you can do is create a new array with a second dimonesion and copy the values over and set the second dimension to a default value.
void Main()
{
int[] sourceCollection = new [] {1,2,3,4,5,6,7} ;
var result = CopyArrayValues(sourceCollection, 2);
result.Dump();
}
//create a new 2d array
T[,] CopyArrayValues<T>(T[] DataSource, int SecondLength)
{
//Initialize the new array
var Target = new T[DataSource.Length, SecondLength];
//Copy values over
for (int i = 0; i < DataSource.Length; i++)
{
Target[i, 0] = DataSource[i];
}
return Target;
}
Output:
If it's ok for you to have array of arrays, you can do something along this pattern:
int[] sourceCollection = new[] { 1, 2, 3, 4, 5, 6, 7 };
int[][] arr = sourceCollection.Select(i => Enumerable.Range(i, 4).ToArray()).ToArray();
I can easily pass a data file to a 2D array if I know the size of the data file, but thats pretty pointless when you want to add and remove data.
How can I instantiate a 2D array of that Data rows length that is global and not out of scope to the rest of the program?
Here is the usual code, for an array of 4 rows and 6 columns, but I want to add/remove data to the data file making it of unknown length in rows.
string[,] allStudentData = new string[4, 6];
string[] allStudents = File.ReadAllLines("data.txt");
for (int i = 0; i < allStudents.Count(); i++)
{
for (int j = 0; j < 6; j++)
{
string[] DataIn = allStudents[i].Split(',');
allStudentData[i, j] = DataIn[j];
}
}
Thanks for your ideas :-)
Why not use something mutable, like a List ?
You can add columns using the .Add() command, , and you can collapse it into an array when you're done with it (.ToArray())
you can do as below
var result = File.ReadAllLines("data.txt").Select(x=>x.Split(',')).ToArray();
You can use a List that holds a custom object (it could be an array) instead of Array and then at the end convert the list to an array with the ToArray extension:
var list = new List<string[]>();
var data1 = new string[2] {"1", "2" };
var data2 = new string[3] {"1", "2", "3" };
list.Add(data1);
list.Add(data2);
list.ToArray(); // converts the list to string[][]
After you are done reading the file you could add easily more items to the list and then at the end write all modifications to the file. If you think, that in future you will need more than the two dimensional array, than it's worth it to create a custom object like:
public class Student
{
public string Name { get; set; }
public int Grade { get; set; }
}
and use this instead of the string[]:
var studentData = new List<Student>();
The maintenance later will be much more easier (adding address, classes, and so on). I admit, you will have a little more work to do when reading and writing, but if the project grows it will pay off.
You can still use LINQ to read the data on one line:
// creates a List<Student>
var studentData = File.ReadAllLines("data.txt")
.Select(row => row.Split(','))
.Select(elements =>
new Student
{
Name = elements[0],
Grade = int.Parse(elements[1])
}).ToList();
If the number of columns is always 6 and only the number of rows is unknown. Just change the first 2 rows of your code to:
string[] allStudents = File.ReadAllLines("data.txt");
string[,] allStudentData = new string[allStudents.Count(), 6];
If the number of columns is unknown you can do this to get a 2D result:
var not2DResult = File.ReadAllLines("data.txt").Select(x => x.Split(',')).ToArray();
var maxRow = not2DResult.Count()-1;
int maxColumn = Enumerable.Select(not2DResult, c => c.Count()).Max()-1;
var result2D = new string[maxRow, maxColumn];
for (int rowNumber = 0; rowNumber < maxRow; rowNumber++)
{
var row = not2DResult[rowNumber];
for (int columnNumber = 0; columnNumber < row.Count(); columnNumber++)
{
result2D[rowNumber, columnNumber] = row[columnNumber];
}
}
Try using a Lists to hold the file information.
var myList = new List<string>();
myList = File.ReadLines("data.txt");
var my2DList = new List<List<string>>();
foreach(string line in myList)
my2DList.Add(line.Split(','));
If you want to know the number of lines, just use:
int numberOfLines = my2DList.Count;
For the number of items in an individual line:
int lengthOfLine3 = my2DList[3].Length;
Probably a really simple one this - I'm starting out with C# and need to add values to an array, for example:
int[] terms;
for(int runs = 0; runs < 400; runs++)
{
terms[] = runs;
}
For those who have used PHP, here's what I'm trying to do in C#:
$arr = array();
for ($i = 0; $i < 10; $i++) {
$arr[] = $i;
}
You can do this way -
int[] terms = new int[400];
for (int runs = 0; runs < 400; runs++)
{
terms[runs] = value;
}
Alternatively, you can use Lists - the advantage with lists being, you don't need to know the array size when instantiating the list.
List<int> termsList = new List<int>();
for (int runs = 0; runs < 400; runs++)
{
termsList.Add(value);
}
// You can convert it back to an array if you would like to
int[] terms = termsList.ToArray();
Edit: a) for loops on List<T> are a bit more than 2 times cheaper than foreach loops on List<T>, b) Looping on array is around 2 times cheaper than looping on List<T>, c) looping on array using for is 5 times cheaper than looping on List<T> using foreach (which most of us do).
Using Linq's method Concat makes this simple
int[] array = new int[] { 3, 4 };
array = array.Concat(new int[] { 2 }).ToArray();
result
3,4,2
If you're writing in C# 3, you can do it with a one-liner:
int[] terms = Enumerable.Range(0, 400).ToArray();
This code snippet assumes that you have a using directive for System.Linq at the top of your file.
On the other hand, if you're looking for something that can be dynamically resized, as it appears is the case for PHP (I've never actually learned it), then you may want to use a List instead of an int[]. Here's what that code would look like:
List<int> terms = Enumerable.Range(0, 400).ToList();
Note, however, that you cannot simply add a 401st element by setting terms[400] to a value. You'd instead need to call Add() like this:
terms.Add(1337);
By 2019 you can use Append, Prepend using LinQ in just one line
using System.Linq;
and then in NET 6.0:
terms = terms.Append(21);
or versions lower than NET 6.0
terms = terms.Append(21).ToArray();
Answers on how to do it using an array are provided here.
However, C# has a very handy thing called System.Collections
Collections are fancy alternatives to using an array, though many of them use an array internally.
For example, C# has a collection called List that functions very similar to the PHP array.
using System.Collections.Generic;
// Create a List, and it can only contain integers.
List<int> list = new List<int>();
for (int i = 0; i < 400; i++)
{
list.Add(i);
}
Using a List as an intermediary is the easiest way, as others have described, but since your input is an array and you don't just want to keep the data in a List, I presume you might be concerned about performance.
The most efficient method is likely allocating a new array and then using Array.Copy or Array.CopyTo. This is not hard if you just want to add an item to the end of the list:
public static T[] Add<T>(this T[] target, T item)
{
if (target == null)
{
//TODO: Return null or throw ArgumentNullException;
}
T[] result = new T[target.Length + 1];
target.CopyTo(result, 0);
result[target.Length] = item;
return result;
}
I can also post code for an Insert extension method that takes a destination index as input, if desired. It's a little more complicated and uses the static method Array.Copy 1-2 times.
Based on the answer of Thracx (I don't have enough points to answer):
public static T[] Add<T>(this T[] target, params T[] items)
{
// Validate the parameters
if (target == null) {
target = new T[] { };
}
if (items== null) {
items = new T[] { };
}
// Join the arrays
T[] result = new T[target.Length + items.Length];
target.CopyTo(result, 0);
items.CopyTo(result, target.Length);
return result;
}
This allows to add more than just one item to the array, or just pass an array as a parameter to join two arrays.
You have to allocate the array first:
int [] terms = new int[400]; // allocate an array of 400 ints
for(int runs = 0; runs < terms.Length; runs++) // Use Length property rather than the 400 magic number again
{
terms[runs] = value;
}
int ArraySize = 400;
int[] terms = new int[ArraySize];
for(int runs = 0; runs < ArraySize; runs++)
{
terms[runs] = runs;
}
That would be how I'd code it.
C# arrays are fixed length and always indexed. Go with Motti's solution:
int [] terms = new int[400];
for(int runs = 0; runs < 400; runs++)
{
terms[runs] = value;
}
Note that this array is a dense array, a contiguous block of 400 bytes where you can drop things. If you want a dynamically sized array, use a List<int>.
List<int> terms = new List<int>();
for(int runs = 0; runs < 400; runs ++)
{
terms.Add(runs);
}
Neither int[] nor List<int> is an associative array -- that would be a Dictionary<> in C#. Both arrays and lists are dense.
You can't just add an element to an array easily. You can set the element at a given position as fallen888 outlined, but I recommend to use a List<int> or a Collection<int> instead, and use ToArray() if you need it converted into an array.
If you really need an array the following is probly the simplest:
using System.Collections.Generic;
// Create a List, and it can only contain integers.
List<int> list = new List<int>();
for (int i = 0; i < 400; i++)
{
list.Add(i);
}
int [] terms = list.ToArray();
one approach is to fill an array via LINQ
if you want to fill an array with one element
you can simply write
string[] arrayToBeFilled;
arrayToBeFilled= arrayToBeFilled.Append("str").ToArray();
furthermore, If you want to fill an array with multiple elements you can use the
previous code in a loop
//the array you want to fill values in
string[] arrayToBeFilled;
//list of values that you want to fill inside an array
List<string> listToFill = new List<string> { "a1", "a2", "a3" };
//looping through list to start filling the array
foreach (string str in listToFill){
// here are the LINQ extensions
arrayToBeFilled= arrayToBeFilled.Append(str).ToArray();
}
Array Push Example
public void ArrayPush<T>(ref T[] table, object value)
{
Array.Resize(ref table, table.Length + 1); // Resizing the array for the cloned length (+-) (+1)
table.SetValue(value, table.Length - 1); // Setting the value for the new element
}
int[] terms = new int[10]; //create 10 empty index in array terms
//fill value = 400 for every index (run) in the array
//terms.Length is the total length of the array, it is equal to 10 in this case
for (int run = 0; run < terms.Length; run++)
{
terms[run] = 400;
}
//print value from each of the index
for (int run = 0; run < terms.Length; run++)
{
Console.WriteLine("Value in index {0}:\t{1}",run, terms[run]);
}
Console.ReadLine();
/*Output：
Value in index 0: 400
Value in index 1: 400
Value in index 2: 400
Value in index 3: 400
Value in index 4: 400
Value in index 5: 400
Value in index 6: 400
Value in index 7: 400
Value in index 8: 400
Value in index 9: 400
*/
If you don't know the size of the Array or already have an existing array that you are adding to. You can go about this in two ways. The first is using a generic List<T>:
To do this you will want convert the array to a var termsList = terms.ToList(); and use the Add method. Then when done use the var terms = termsList.ToArray(); method to convert back to an array.
var terms = default(int[]);
var termsList = terms == null ? new List<int>() : terms.ToList();
for(var i = 0; i < 400; i++)
termsList.Add(i);
terms = termsList.ToArray();
The second way is resizing the current array:
var terms = default(int[]);
for(var i = 0; i < 400; i++)
{
if(terms == null)
terms = new int[1];
else
Array.Resize<int>(ref terms, terms.Length + 1);
terms[terms.Length - 1] = i;
}
If you are using .NET 3.5 Array.Add(...);
Both of these will allow you to do it dynamically. If you will be adding lots of items then just use a List<T>. If it's just a couple of items then it will have better performance resizing the array. This is because you take more of a hit for creating the List<T> object.
Times in ticks:
3 items
Array Resize Time: 6
List Add Time: 16
400 items
Array Resize Time: 305
List Add Time: 20
I will add this for a another variant. I prefer this type of functional coding lines more.
Enumerable.Range(0, 400).Select(x => x).ToArray();
You can't do this directly. However, you can use Linq to do this:
List<int> termsLst=new List<int>();
for (int runs = 0; runs < 400; runs++)
{
termsLst.Add(runs);
}
int[] terms = termsLst.ToArray();
If the array terms wasn't empty in the beginning, you can convert it to List first then do your stuf. Like:
List<int> termsLst = terms.ToList();
for (int runs = 0; runs < 400; runs++)
{
termsLst.Add(runs);
}
terms = termsLst.ToArray();
Note: don't miss adding 'using System.Linq;' at the begaining of the file.
This seems like a lot less trouble to me:
var usageList = usageArray.ToList();
usageList.Add("newstuff");
usageArray = usageList.ToArray();
Just a different approach:
int runs = 0;
bool batting = true;
string scorecard;
while (batting = runs < 400)
scorecard += "!" + runs++;
return scorecard.Split("!");
int[] terms = new int[400];
for(int runs = 0; runs < 400; runs++)
{
terms[runs] = value;
}
static void Main(string[] args)
{
int[] arrayname = new int[5];/*arrayname is an array of 5 integer [5] mean in array [0],[1],[2],[3],[4],[5] because array starts with zero*/
int i, j;
/*initialize elements of array arrayname*/
for (i = 0; i < 5; i++)
{
arrayname[i] = i + 100;
}
/*output each array element value*/
for (j = 0; j < 5; j++)
{
Console.WriteLine("Element and output value [{0}]={1}",j,arrayname[j]);
}
Console.ReadKey();/*Obtains the next character or function key pressed by the user.
The pressed key is displayed in the console window.*/
}
/*arrayname is an array of 5 integer*/
int[] arrayname = new int[5];
int i, j;
/*initialize elements of array arrayname*/
for (i = 0; i < 5; i++)
{
arrayname[i] = i + 100;
}
To add the list values to string array using C# without using ToArray() method
List<string> list = new List<string>();
list.Add("one");
list.Add("two");
list.Add("three");
list.Add("four");
list.Add("five");
string[] values = new string[list.Count];//assigning the count for array
for(int i=0;i<list.Count;i++)
{
values[i] = list[i].ToString();
}
Output of the value array contains:
one
two
three
four
five
You can do this is with a list. here is how
List<string> info = new List<string>();
info.Add("finally worked");
and if you need to return this array do
return info.ToArray();
Here is one way how to deal with adding new numbers and strings to Array:
int[] ids = new int[10];
ids[0] = 1;
string[] names = new string[10];
do
{
for (int i = 0; i < names.Length; i++)
{
Console.WriteLine("Enter Name");
names[i] = Convert.ToString(Console.ReadLine());
Console.WriteLine($"The Name is: {names[i]}");
Console.WriteLine($"the index of name is: {i}");
Console.WriteLine("Enter ID");
ids[i] = Convert.ToInt32(Console.ReadLine());
Console.WriteLine($"The number is: {ids[i]}");
Console.WriteLine($"the index is: {i}");
}
} while (names.Length <= 10);