Develop Reference

Determine if array contains all zeroes

I create the following array like this:
array<UInt16>^ temp = gcnew array<UInt16>(1000);
How do I determine if this entire array has been filled with zero or not.
I think I may be able to use TrueForAll(T) but I'm not sure.

var allElementsAreZero = temp.All(o => o == 0);
Simple as that.
It'll return when it finds one that doesn't satisfy the condition, so may not necessarily iterate through your whole collection:
"The enumeration of source is stopped as soon as the result can be determined."
https://msdn.microsoft.com/en-us/library/bb548541(v=vs.110).aspx

This should work properly (here I used LINQ):
IEnumerable<int> values = new List<int>(); // Or use any array type instead of List.
... Add your values here ...
var allAreZero = !values.Any(v => v != 0);
P.S. the array class inherits IEnumerable.
And here is a solution with foreach:
var isAllZero = true;
foreach (var value in values)
{
if (value != 0)
{
isAllZero = false;
break;
}
}
UPDATE
The really difference between TrueForAll, and my LINQ code is: LINQ code uses the fluent (or maybe also query) syntax, where TrueForAll is just a normal function where you send the array as a parameter.

initialize a counter from 0 then use for loop to interate through the array and increment the counter whenever it finds 0, and at the end compare the counter with size of array if its equal, it has all zeros

Reading the C++/CLI specification, it has been filled with
0s because you created it with a "new-expression" and the default value of the element type is 0.
24.2 CLI array creation
CLI array instances are created by new-expressions containing gcnew (§15.4.6) or …
Elements of CLI arrays created by new-expressions are always initialized to their default value.

Change value of each element by linq

Is it possible to do sth like this in LINQ:
int[] d = new int[c.Length + 1];
int e = 1;
d.ToList().ForEach(r =>
{
r = e;
e++;
});
?.
When I did this, it returned me sequence of zeros.
Regards.

Yes, it would, for two reasons:
You're creating a copy of the original array as a List<int>, and then trying to modify the List<int>. That wouldn't modify the array.
Your lambda expression changes the value of the parameter, that's all. It doesn't modify the list.
Basically, LINQ is for querying. Don't even bother trying to do this: use a for loop if you want to modify the collection.
However, if your aim is to produce an array of 1...(c.Length+1), just use Enumerable.Range:
var array = Enumerable.Range(1, c.Length + 1).ToArray();

Search for an existing object in a list

This is my first question here so I hope I'm doing right.
I have to create a List of array of integer:
List<int[]> finalList = new List<int[]>();
in order to store all the combinations of K elements with N numbers.
For example:
N=5, K=2 => {1,2},{1,3},{1,4},...
Everything is all right but I want to avoid the repetitions of the same combination in the list({1,2} and {2,1} for example). So before adding the tmpArray (where I temporally store the new combination) in the list, I want to check if it's already stored.
Here it's what I'm doing:
create the tmpArray with the next combination (OK)
sort tmpArray (OK)
check if the List already contains tmpArray with the following code:
if (!finalList.Contains(tmpArray))
finalList.Add(tmpArray);
but it doesn't work. Can anyone help me with this issue?

Array is a reference type - your Contains query will not do what you want (compare all members in order).
You may use something like this:
if (!finalList.Any(x => x.SequenceEqual(tmpArray))
{
finalList.Add(tmpArray);
}
(Make sure you add a using System.Linq to the top of your file)
I suggest you learn more about value vs. reference types, Linq and C# data structure fundamentals. While above query should work it will be slow - O(n*m) where n = number of arrays in finalList and m length of each array.
For larger arrays some precomputing (e.g. a hashcode for each of the arrays) that allows you a faster comparison might be beneficial.

If I remember correctly, contains will either check the value for value data types or it will check the address for object types. An array is an object type, so the contains is only checking if the address in memory is stored in your list. You'll have to check each item in this list and perform some type of algorithm to check that the values of the array are in the list.
Linq, Lambda, or brute force checking comes to mind.
BrokenGlass gives a good suggestion with Linq and Lambda.
Brute Force:
bool itemExists = true;
foreach (int[] ints in finalList)
{
if (ints.Length != tmpArray.Length)
{
itemExists = false;
break;
}
else
{
// Compare each element
for (int i = 0; i < tmpArray.Length; i++)
{
if (ints[i] != tmpArray[i])
{
itemExists = false;
break;
}
}
// Have to check to break from the foreach loop
if (itemExists == false)
{
break;
}
}
}
if (itemExists == false)
{
finalList.add(tmpArray);
}

C# Sort object array by specific parameter

I am relatively new to programming. I have an array of objects which isn't necessarily full (may include null rows). And I want to sort it by one of the class parameters "int moveScore".
This is my array (currently holds only 32 entries)
Score[] firstPlyScore = new Score[1000];
I tried 2 things for sorting
1
In the "Score" class, i inherited "IComparable" and used the "CompareTo" method as follows
public int CompareTo(object obj)
{
Score x = (Score)obj;
if (this.moveScore < x.moveScore)
return -1;
if (this.moveScore > x.moveScore)
return 1;
return 0;
}
I called it using;
Array.Sort(firstPlyScore);
The problem is that it does sort correctly but at the end of the array. Meaning rows 0-966 are "null" and 967-999 are sorted correctly (967 with highest "int", 999 with lowest).
Is there any way to fix this.
2
I also tried this
Array.Sort(firstPlyScore, delegate
(Score x, Score y) { return x.moveScore.CompareTo(y.moveScore); });
Here the problem was that it crashed when it reached a "null" row.
Help most appreciated!

The default comparison behavior is for null values to be ordered before non-null values. If you want to override this behavior, a custom Comparison<Score> like in your second example would be the way to go.
delegate (Score x, Score y) {
if (x == null)
return y == null ? 0 : 1;
if (y == null)
return -1;
return x.moveScore.CompareTo(y.moveScore);
}
This will keep the null items at the end of the array.
To sort in descending order, just swap the x and y references in the last line.

firstPlyScore = firstPlyScore
.Where(x => x != null)
.OrderByDescending(x => x.moveScore)
.ToArray();

You can use Linq to Entities to sort and then convert back to an array it will re-size your array to the correct length needed without null issue
var list = firstPlyScore.OrderByDescending(x => x.MoveScore).ToList();
//here how you can get always 1000 array length as you asked
for (int i = list.Count-1; i < 1000; i++)
{
list.Add(null);
}
firstPlyScore = list.ToArray();
}

In the beginning of your compare method
if(obj == null) return 0;

The problem is that it does sort correctly but at the end of the
array. Meaning rows 0-966 are "null" and 967-999 are sorted correctly
(967 with highest "int", 999 with lowest). Is there any way to fix
this.
If you need something, whose size can change, you are looking for a List<int>, instead of using arrays.
Arrays should be used for Lists that do not change (e.g. a chess board).
The List also provides you a method called Sort.
As mentioned by others, you can also use LINQ to achieve what you seek for.

Do you really need to keep 1000 items in the list even if most of them are null ?
I would suggest to check the logic behind it to see if you can prevent that because that's taking a lot of space for nothing.
Otherwise, 2 possibilities:
Check for Obj == null in your compare function. But it might still fail if the comparing item is null
Create a custom class for your score and make Icomparable (Check this link for several example about how to sort arrays

C# Loop Through An Array

I am completely new to C#. I am trying to loop through a short array, where the string elements in the array are placed at the end of a website search. The code:
int n = 1;
string[] s = {"firstitem","seconditem","thirditem"}
int x = s.Max(); // note, from my research this should return the maximum value in the array, but this is the first error
x = x + 1
while (n < x)
{
System.Diagnostics.Process.Start("www.website.com/" + b[0]);
b[]++; // this also generates an error "identifier expected"
}
My coding, logic or both are wrong. Based on what I've read, I should be able to get the maximum value in an array (as an int), then add to the arrays value while a WHILE loop adds each value in the array at the end of the website (and then stops). Note, that on the first error, I tried coding it differently, like the below:
int x = Convert.ToInt32(s.Max);
However, it generates an overload error. If I'm reading things correctly, MAX should find the maximum value in a sequence.

foreach(var str in s)
{
System.Diagnostics.Process.Start("www.website.com/" + str);
}

You have a collection of strings. The largest string is still a string, not an int. Since s.Max() is a string, and you're assinging it to a variable of type int: int x = s.Max(); the compiler (correctly) informs you that the types do not match. You need to convert that string to an int. Since, looking at your data, they aren't integers, and I see no sensible way of converting those strings into integers, I see no reasonable solution. What integer should "firstitem" be?
If you just want to execute some code for each item in the array then use one of these patterns:
foreach(string item in s)
{
System.Diagnostics.Process.Start("www.website.com/" + item);
}
or
for(int i = 0; i < s.Length; i++)
{
System.Diagnostics.Process.Start("www.website.com/" + s[i]);
}

You're missing a couple of semi-colons
x should presumably be the Length of the array, not the largest value in it
You need to increment x inside of your loop - at the end of it, not outside of it
You should actually be incrementing n, not x
n should be starting at 0, not at 1
Inside the loop you're using b[0] where you probably want to use b[n]
I'm no C++ guru, but I have no idea what b[]++ might mean
As other answers have mentioned, you may want to use a for or foreach instead of a while.
Make an effort to go through some introductory tutorials. Trial and error can be a useful tool, but there's no need to fall back on that when learning the very basics

Following is an image to point out what are the errors of your code:
After the correction, it would be:
int n=1;
string[] s= { "firstitem", "seconditem", "thirditem" };
int x=s.Length;
while(n<x) {
System.Diagnostics.Process.Start("www.website.com/"+s[n]);
n++; // or ++n
}
And we can make it more semantic:
var items=new[] { "firstitem", "seconditem", "thirditem" };
for(int index=1, count=items.Length; index<count; ++index)
Process.Start("www.website.com/"+items[index]);
If the starting order doesn't matter, and we can use foreach instead, and we can use Linq to make the code even simpler:
var list=(new[] { "firstitem", "seconditem", "thirditem" }).ToList();
list.ForEach(item => Process.Start("www.website.com/"+item));
and we might quite often write in another form:
foreach(var item in new[] { "firstitem", "seconditem", "thirditem" })
Process.Start("www.website.com/"+item);

from the sample
var processList = (new string[]{"firstitem","seconditem","thirditem"})
.Select(s => Process.Start("www.website.com/" + s))
.ToList();
and here is a test version that outputs to console
(new string[] { "firstitem", "seconditem", "thirditem" })
.Select(s => { Console.WriteLine(#"www.website.com/" + s); return s; })
.ToList();
note: Select requires a return type and the .ToList() enforces evaluation.