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Evaluating 0 when trying to find the smallest integer fails

I'm trying to do a simple sorting of my own (I know Array.Sort() exists), receiving a user input array and then calling the method sortMyArray() to sort the numbers from smallest to largest. Which does what intended, except for when I try to find the smallest number of an array that contains 0.
As you will see: I'm initialising the variable smallest to the value int.MaxValue at each iteration, but if the array contains a 0, it stays set to to the int.MaxValue.
static int findSmallest(int[] original, int[] sorted, int smallest)
{
for (int i = 0; i < sorted.Length; i++)
{
if (original[i] < smallest & !sorted.Contains(original[i]))
{
smallest = original[i];
}
}
return smallest;
}
static int[] sortMyArray(int[] original)
{
int[] sorted = new int[original.Length];
for (int i = 0; i < sorted.Length; i++)
{
int smallest = int.MaxValue;
smallest = findSmallest(original, sorted, smallest);
sorted[i] = smallest;
}
return sorted;
}
sortMyArray(inputArray);
My question is, how can I make sure 0 is properly handled?
The code behaves as intended for positive and negative integer values, but what is causing the 0 to not work?
Edit: For example, if the inputArray contains {5, -1, 7, 0, 33}, then the method will return it sorted as such: {-1, 5, 7, 33, 2147483647}.

With !sorted.Contains(original[i]) you skip over any value that is already in the array. sorted is initialized to all 0's so it will never set smallest = 0. In your last iteration in sortMyArray, smallest will be equal to int.Max. Note, this will also happen when you have the same element twice. Since you want to implement your own sorting method (and not use Array.Sort), you should look into various sorting algorithms (i.e. Merge Sort, Quick Sort, etc.) as yours won't work as intended.

c# foreach loop not able to add literals in an array

Firstly I know that I can't use a foreach loop in C# to add values in let's say an array... But why? Why for example I can't do this
int[] numbers = { 1, 4, 3, 5, 7, 9 };
foreach (int item in numbers)
{
numbers[item] = 2;
}
Does it have something to do with the actual realisation of the foreach loop in the back-end? And how does the foreach loop exactly work? I know that it goes through the whole collection(array) but how exactly?

You are passing in the value of an item (your variable, item, will be the value of the array at each position in sequence, not the index) in the array as the index. The index used there is meant to be the position of the item you are attempting to access, not the value. So each iteration of the loop you are calling:
numbers[1]
numbers[4]
numbers[3]
numbers[5]
numbers[7]
numbers[9]
The array has 6 numbers, so when you get to numbers[7], you are asking for a value that is not there, hence the exception.
A better method of doing what you are trying to do would be:
for(int i = 0; i < numbers.Length; i++)
{
numbers[i] = 2;
}
On each iteration of this loop you would be accessing:
numbers[0]
numbers[1]
numbers[2]
numbers[3]
numbers[4]
numbers[5]

I'm looking at this:
numbers[item] = 2;
In this expression, you're using the item variable like an index, as if it had the values 1, 2, 3, 4, etc. That's not how the foreach iteration variable works for C#. The only language I know that does it this way is Javascript.
Remember that foreach and for are not the same thing. Just about every other language, including C#, gives you the actual array values in the item variable of a foreach loop: 1,4, 3, 5 etc. Now, these are integers, so you could try to use them as indexes. You can run the loop for a while like that... until you get to the value 7. At this point, your array only has six values. You're trying to do this:
numbers[7] = 2;
for an array where the largest valid index you can use is 5.
This is true even taking your modification of the array into account. Let's look at the array after each iteration through the loop:
{ 1, 4, 3, 5, 7, 9 } //initial state
{ 1, 2, 3, 5, 7, 9 } // after 1st iteration (index 0). Value at index 0 is 1, so item as index 1 is set to 2
{ 1, 2, 2, 5, 7, 9 } // after 2nd iteration (index 1). Value at index 1 is now 2, so item at index 2 is set to 2
{ 1, 2, 2, 5, 7, 9 } // after 3rd iteration (index 2). Value at index 2 is now 2, so item at index 2 is set to 2
{ 1, 2, 2, 5, 7, 2 } // after 4th iteration (index 3). Value at index 3 is 5, so item at index 5 is set to 2
// The 5th iteration (index 4). Value at index 4 is 7, which is beyond the end of the array
For the why of this... it sounds like you're used to a more dynamic language. Some these other languages, like php or Javascript, don't have real arrays at all in the pure computer science sense. Instead, they have collection types they'll call an array, but when you get down to it are really something different.
C# has real arrays, and real arrays have a fixed size. If what you really want is a collection, C# has collections, too. You can use List<T> objects, for example, to get an array-like collection you can append to easily.
For the other languages, the results vary depending on what you're talking about, but for the most permissive the result of your 5th iteration is something like this:
{ 1, 2, 2, 5, 7, 2, ,2 }
Note the missing value at index 6. That kind of things leads to mistakes that slip through your tests and don't show up until run-time. You also need to start wondering just how densely or sparsely the array will be filled, because the best strategy for handling these arrays can vary wildly depending on your answer... everything from just a big backing array with empty nodes that the programmer has to know about all the way to Hashtables and Dictionaries. And, by the way, C# again has these options available to you.

You need to step through your code in a debugger.
A for statement is more like a while statement, not like a foreach.
The line int[] numbers = { 1, 4, 3, 5, 7, 9 }; create this:
numbers[0] = 1;
numbers[1] = 4;
numbers[2] = 3;
numbers[3] = 5;
numbers[4] = 7;
numbers[5] = 9;
Your foreach statement does this:
numbers[1] = 2;
numbers[4] = 2;
numbers[3] = 2;
numbers[5] = 2;
numbers[7] = 2; <- this line overflows your array!
numbers[9] = 2; <- and so would this.
You have to learn the difference between an array index and an array value.

You need to create counter, in other case you trying to access item outside of array
int[] numbers = new int[]{ 1, 4, 3, 5, 7, 9 };
int i = 0;
foreach (int item in numbers)
{
numbers[i] = 2;
i++;
}
// Print the items of the array
foreach (int item in numbers)
{
Console.WriteLine(item);
}

Get max from a sub array in C#

I have a question, lets say I have an array:
var array = new int[] { 7, 16, 4, 9, 865, 3, -8, 56};
I want to get the max value from index (lets say index 4), how do I do that?
Is there something like:
array.fromIndex(4).max()
also, I tried to go simple and did
(array + 4).max()
but get an error
"operator '+' cannot be applied"
Why is that?
Thank you!

also, I tried to go simple and did
(array + 4).max()
but get an error "operator '+' cannot be applied", why is that?
In C# array is not a pointer that you can calculate with. So the operator + is not defined to perform such an operation.
If you want to start searching the max value from a certain index on you can skip all the values up to this point:
int maxValue = array.Skip(4).Max();
EDIT:
Inspired by the suggested of #jdphenix in the comment:
If you want to have more control over the range where you want to search the maximum then the Take method could be of great help. This combination would allow you to set the range of your sub array:
var array = new int[] { 7, 16, 4, 9, 865, 3, -8, 56 };
int startIndex = 4;
int numberOfElements = 3;
array.Skip(startIndex).Take(numberOfElements).Max();
if you want to specify the start- and end-index it would look like this:
int startIndex = 4;
int endIndex = 7;
array.Skip(startIndex).Take(endIndex - startIndex).Max();

Find smallest number in given range in an array

Hi i have an array of size N. The array values will always have either 1, 2, 3 integer values only. Now i need to find the lowest number between a given range of array indices. So for e.g. array = 2 1 3 1 2 3 1 3 3 2. the lowest value for ranges like [2-4] = 1, [4-5] = 2, [7-8] = 3, etc.
Below is my code :
static void Main(String[] args) {
string[] width_temp = Console.ReadLine().Split(' ');
int[] width = Array.ConvertAll(width_temp,Int32.Parse); // Main Array
string[] tokens_i = Console.ReadLine().Split(' ');
int i = Convert.ToInt32(tokens_i[0]);
int j = Convert.ToInt32(tokens_i[1]);
int vehicle = width[i];
for (int beg = i+1; beg <= j; beg++) {
if (vehicle > width[beg]) {
vehicle = width[beg];
}
}
Console.WriteLine("{0}", vehicle);
}
The above code works fine. But my concern is about efficiency. In above I am just taking one set of array range, but in actual there will be n number of ranges and I would have to return the lowest for each range. Now the problem is if there is a range like [0-N], N is array size, then I would end up comparing all the items for lowest. So I was wondering if there is a way around to optimize the code for efficiency???

I think it is a RMQ (Range Minimum Query) and there is several implementation which may fit your scenario.
Here is a nice TopCoder Tutorial cover a lot of them, I recommend two of them:
Using the notation in the tutorial, define <P, T> as <Preprocess Complexity, Query Complexity>, there is two famous and common implementation / data structure which can handle RMQ: Square Rooting Array & Segment Tree.
Segment Tree is famous yet hard to implement, it can solve RMQ in <O(n), O(lg n)> though, which has better complexity than Square Rooting Array (<O(n), O(sqrt(n))>)
Square Rooting Array (<O(n), O(sqrt(n))>)
Note That It is not a official name of the technique nor any data structure, indeed I do not know if there is any official naming of this technique since I learnt it...but here we go
For query time, it is definitely not the best you can got to solve RMQ, but it has an advantage: Easy Implementation! (Compared to Segment Tree...)
Here is the high level concept of how it works:
Let N be the length of the array, we split the array into sqrt(N) groups, each contain sqrt(N) elements.
Now we use O(N) time to find the minimum value of each groups, store them into another array call M
So using the above array, M[0] = min(A[0..2]), M[1] = min(A[3..5]), M[2] = min(A[6..8]), M[3] = min(A[9..9])
(The image from TopCoder Tutorial is storing the index of the minimum element)
Now let's see how to query:
For any range [p..q], we can always split this range into 3 parts at most.
Two parts for the left boundaries which is some left over elements that cannot be form a whole group.
One part is the elements in between, which forms some groups.
Using the same example, RMQ(2,7) can be split into 3 parts:
Left Boundary (left over elements): A[2]
Right Boundary (left over elements): A[6], A[7]
In between elements (elements across whole group): A[3],A[4],A[5]
Notice that for those in between elements, we have already preprocessed their minimum using M, so we do not need to look at each element, we can look and compare M instead, there is at most O(sqrt(N)) of them (it is the length of M afterall)
For boundary parts, as they cannot form a whole group by definition, means there is at most O(sqrt(N)) of them (it is the length of one whole group afterall)
So combining two boundary parts, with one part of in between elements, we only need to compare O(3*sqrt(N)) = O(sqrt(N)) elements
You can refer to the tutorial for more details (even for some pseudo codes).

You could do this using Linq extension methods.
List<int> numbers = new List<int> {2, 1, 3, 1, 2, 3, 1, 3, 3, 2};
int minindex =1, maxindex =3, minimum=-1;
if(minindex <= maxindex && maxindex>=0 && maxindex >=0 && maxindex < numbers.Count())
{
minimum = Enumerable.Range(minindex, maxindex-minindex+1) // max inclusive, remove +1 if you want to exclude
.Select(x=> numbers[x]) // Get the elements between given indices
.Min(); // Get the minimum among.
}
Check this Demo

This seems a fun little problem. My first point would be that scanning a fixed array tends to be pretty fast (millions per second), so you'd need a vast amount of data to warrant a more complex solution.
The obvious first thing, is to break from the loop when you have found a 1, as you've found your lowest value then.
If you want something more advanced.
Create a new array of int. Create a pre load function that populates each item of this array with the next index where it gets lower.
Create a loop that uses the new array to skip.
Here is what I mean. Take the following arrays.
int[] intialArray = new int[] { 3, 3, 3, 3, 2, 2, 2, 1 };
int[] searchArray = new int[] { 4, 4, 4, 4, 7, 7, 7, 7 };
So the idea is to find the lowest between positions 0-7.
Start at initialArray[0] and get value 3.
Read searchArray[0] and get the value 4. The 4 is the next index where the number is lower.
Read initialArray[4] and get the value 2.
etc.
So basically you'd need to put some effort to build the searcharray, but onces it's complete you would scan each range much faster.

Form your looping like the following:
int[] inputArray = { 2, 1, 3, 1, 2, 3, 1, 3, 3, 2 };
int minIndex = 2;
int maxIndex = 5;
int minVal = 3;
for (int i = minIndex; i <= maxIndex; i++)
{
if (inputArray[i] <= minVal)
minVal = inputArray[i];
}
Console.WriteLine("Minimum value in the Given range is ={0}", minVal);

How can we find items count in the C# integer array?

I need to find items count in the C# array which type is integer.
What I mean is;
int[] intArray=new int[10]
int[0]=34
int[1]=65
int[2]=98
Items count for intArray is 3.
I found the code for strArray below but It doesn't work for int arrays.
string[] strArray = new string[50];
...
int result = strArray.Count(s => s != null);

Well, first you have to decide what an invalid value would be. Is it 0? If so, you could do this:
int result = intArray.Count(i => i != 0);
Note that this only works because, by default, elements of an int array are initialized to zero. You'd have to fill the array with a different, invalid value beforehand if 0 ends up being valid in your situation.
Another way would be to use a nullable type:
int?[] intArray = new int?[10];
intArray[0] = 34;
intArray[1] = 65;
intArray[2] = 98;
int result = intArray.Count(i => i.HasValue);

While itsme86 provided you a good answer to your actual question, I suspect you may be better off reconsidering how you write this entirely.
If this is your goal, I would recommend thinking about this differently. Instead of allocating a fixed size array, and only assigning specific values to it, you might want to consider using a List<int>:
List<int> intList = new List<int>();
intList.Add(34);
intList.Add(65);
intList.Add(98);
The number of items will always be intList.Count, and you can add as many items as you wish this way, without worry about the "allocated size", since the list will automatically grow as needed. It also won't provide you bad results if you add 0 to the list as an actual value, where counting non-zero elements will not count a zero if it's a valid value.
Note that you can also access the items by index, just like you do with an array:
int secondValue = intList[1]; // Access like you do with arrays

int[] intArray=new int[3] // Edit: Changed this to 3 to make my answer work. :)
int[0]=34
int[1]=65
int[2]=98
int count = intArray.Length; // <-- Is this what you're after?
Edit:
Ahem. As was so humbly pointed out to me, Length will return the total number of elements in the array, which in your example would have been 10. If you are looking for the number of non-zero elements in the array, you should do as suggested in some of the other answers.

When you initialize an integer array without specifying any values, C# assigns a value of zero to every element. So if zero isn't a valid value for your array, you could always test for that.
Alternatively, you could initialize the elements of your array to some value that is invalid in your context (ie if negative numbers aren't valid, initialize to -1), and then loop through the array counting the valid elements.

If the array is guaranteed to only be accessed in sequence, you can beat the full iterative IEnumerable Count (for larger arrays) with a little divide and conquer, e.g.
static int DivideCount(int[] arr, int idx, int bottom, int top)
{
if (idx <= 0)
return 0;
else if (idx >= arr.Length - 1)
return arr.Length;
else if (arr[idx] == 0 && arr[idx - 1] != 0)
return idx;
else if (arr[idx] == 0 && arr[idx - 1] == 0)
return DivideCount(arr, bottom + ((idx - bottom) / 2), bottom, idx);
else if (arr[idx] != 0 && arr[idx - 1] != 0)
return DivideCount(arr, top - ((top - idx) / 2), idx, top);
else
return -1; // hello compiler
}
int[] intArray = new int[10];
intArray[0] = 35;
intArray[1] = 65;
intArray[2] = 98;
var count = DivideCount(intArray, intArray.Length / 2, 0, intArray.Length);

None of the previous solutions are optimal if someone other than you initialized the array (i.e. you don't have the option of initializing the array values to invalid values -- null, -1, etc.).
Suppose you have an array:
var arr = new[] {0, 10, 18, 0, 20, 0, 0, 0, 0, 0, 0, 0};
If you simply count the number of zero entries:
int result = arr.Count(i => i != 0);
Count() returns 3, when in reality 5 entries have been initialized. An example would be an array of raw bytes that were read out of an audio file into a buffer, and you want to know the index of the last element that was read.
An alternative that isn't perfect but could do what you're looking for is to look for the last non-zero entry, as described here: Linq - Get the Index of the Last Non-Zero Number of Array