I am fairly new to this and trying to learn. I am struggling trying to make a loop to find the max value in an array. I am not sure what I am doing wrong. I have searched everywhere and seen several people do it the way i am but do not know what i am missing…
static void Main(string[] args)
{
int[] Numbs = new int[10];
Numbs[0] = 56;
Numbs[1] = 77;
Numbs[2] = 23;
Numbs[3] = 12;
Numbs[4] = 88;
Numbs[5] = 59;
Numbs[6] = 97;
Numbs[7] = 33;
Numbs[8] = 38;
Numbs[9] = 64;
string[] Names = new string[10] {"John", "George", "Henry", "Larry", "Bart", "Luke", "Tim",
"Frank", "Conor", "Joe"};
FindMax(Numbs[9],9);
}
static int FindMax(int arrayNumbs, int arrayNumbsLength)
{
int Greatest = -1;
for (int Count = 0; Count <= arrayNumbsLength; Count++)
if (arrayNumbs[Count] > Greatest)
{
Console.WriteLine(Count);
Greatest = arrayNumbs;
Console.WriteLine(Greatest);
}
return Greatest;
The most basic change would be:
static int FindMax(int[] arrayNumbs)
{
...
for (int Count = 0; Count < arrayNumbs.Length; Count++)
...
}
The rest is just fine. There are some ways to make it better, but I'm guessing this is a school assignment and you'll get there eventually.
I can see few things that are issues with your code:
Your method defines first parameter as an integer (int arrayNumbs), it should say int[] arrayNumbs since you're passing an array, not a single integer
in your function call FindMax(Numbs[9], 9) you pass an integer as the first argument instead of an array (which didn't give you an error since it's how you defined the method, see above). Second argument is a lie, your array's size is 10, not 9 (remember about first element having index [0])
Inside your method you want to assign the integer to your variable, not the whole array (which would give you an error). Should say Greatest = arrayNumbs[Count]
You can use a List() instead of the array type. A list is dynamic and will expand automatically. In the example below I create the numbs list and use LINQ to get the max value.
var numbs = new List<int>
{
56, 77, 23, 12, 88, 59, 97, 33, 38, 65
};
var max = numbs.Max();
Consider I have an Array,
int[] i = {1,2,3,4,5};
Here I have assigned values for it. But in my problem I get these values only at runtime.
How can I assign them to an array.
For example:
I get the max size of array from user and the values to them now how do I assign them to the array int [].
Or can I use anyother data types like ArrayList etc which I can cast to Int[] at the end?
Well, the easiest is to use List<T>:
List<int> list = new List<int>();
list.Add(1);
list.Add(2);
list.Add(3);
list.Add(4);
list.Add(5);
int[] arr = list.ToArray();
Otherwise, you need to allocate an array of suitable size, and set via the indexer.
int[] arr = new int[5];
arr[0] = 1;
arr[1] = 2;
arr[2] = 3;
arr[3] = 4;
arr[4] = 5;
This second approach is not useful if you can't predict the size of the array, as it is expensive to reallocate the array every time you add an item; a List<T> uses a doubling strategy to minimize the reallocations required.
You mean?
int[] array = { 1, 2, 3, 4, 5 };
array = new int[] { 1, 3, 5, 7, 9 };
array = new int[] { 100, 53, 25, 787, 39 };
array = new int[] { 100, 53, 25, 787, 39, 500 };
Use List<int> and then call ToArray() on it at the end to create an array. But do you really need an array? It's generally easier to work with the other collection types. As Eric Lippert wrote, "arrays considered somewhat harmful".
You can do it explicitly though, like this:
using System;
public class Test
{
static void Main()
{
int size = ReadInt32FromConsole("Please enter array size");
int[] array = new int[size];
for (int i=0; i < size; i++)
{
array[i] = ReadInt32FromConsole("Please enter element " + i);
}
Console.WriteLine("Finished:");
foreach (int i in array)
{
Console.WriteLine(i);
}
}
static int ReadInt32FromConsole(string message)
{
Console.Write(message);
Console.Write(": ");
string line = Console.ReadLine();
// Include error checking in real code!
return int.Parse(line);
}
}
If you want an array, whose size varies during the execution, then you should use another data structure. A generic List will do. Then, you can dynamically add elements to it.
Edit: Marc posted his answer while I was writing mine. This was exactly what I meant.
You could just use the below line instead of calling a separate function:
using System;
public class Test
{
static void Main()
{
Console.WriteLine("Please enter array size");
int size = Convert.ToInt32(Console.ReadLine());
int[] array = new int[size];
for (int i=0; i < size; i++)
{
Console.WriteLine("Please enter element " + i);
array[i] = Convert.ToInt32(Console.ReadLine());
}
Console.WriteLine("Finished:");
foreach (int i in array)
{
Console.WriteLine(i);
}
}
I am using C# and i am trying to find the the average of 5 values but i can only use 2 variables.
How can you input 5 integers into one variable and display the average of said integers
You can use List like this:
var list = new List<int>(){ 1, 2, 3, 4, 5 };
var average = list.Average();
using Average you'll get average of all values in list
Here you have all functions of Enumerable, you can for e.g. sum all values with Sum
Use a collection like a List<int> and the extension method Enumerable.Average:
List<int> numbers = new List<int>{ 10, 20, 30, 40, 50 };
double average = numbers.Average(); // 30.0
Use List.Add to add single integers:
numbers.Add(1);
numbers.Add(2);
numbers.Add(3);
// ...
Take the input values in a Integer list or array then use the following code
List<int> intlist=new List<int>();
intlist.Add(2);
intlist.Add(3);
..
..
var average= intlist.Average();
Using Average will computes the average of a sequence of all the integers in the list.
UPDATE: or if the case is to use integers only then you need to use the following code (Remember to validate the readline() entries)
public decimal Average()
{
int value = 0;
for(int i=0;i<5;i++)
{
value+=ConvertToInt32(Console.ReadLine());
}
return value/5;
}
What about using array? I think array is one variable in your case
int[] input = new int[5];
input[0] = 5;
input[1] = 40;
input[2] = 15;
input[3] = 50;
input[4] = 25;
int sum = 0;
foreach(int i in input)
{
sum = sum + i;
}
sum = sum / input.Length;
Console.WriteLine(sum.ToString());
#up Yeah that's better way!
You dont need arrays, or lists or anything remotely similar. Pseudo-code:
private int sum = 0;
private int count = 0;
while (user inputs valid number)
{
sum += userInput;
count++;
}
return sum / count;
Only two variables.
If you just want solution without List<int> then here it is
int[] arr=new int[5];
arr[0]=10;arr[1]=20;...arr[4]=50;
int sum=0;
foreach(int x in arr)
{
s+=x;
}
s=s/arr.Length;//s is average
If you want list
List<int> list = new List<int>(){ 1, 2, 3, 4, 5 };
var average = list.Average();
Is there a built in function in .NET 2.0 that will take two arrays and merge them into one array?
The arrays are both of the same type. I'm getting these arrays from a widely used function within my code base and can't modify the function to return the data in a different format.
I'm looking to avoid writing my own function to accomplish this if possible.
In C# 3.0 you can use LINQ's Concat method to accomplish this easily:
int[] front = { 1, 2, 3, 4 };
int[] back = { 5, 6, 7, 8 };
int[] combined = front.Concat(back).ToArray();
In C# 2.0 you don't have such a direct way, but Array.Copy is probably the best solution:
int[] front = { 1, 2, 3, 4 };
int[] back = { 5, 6, 7, 8 };
int[] combined = new int[front.Length + back.Length];
Array.Copy(front, combined, front.Length);
Array.Copy(back, 0, combined, front.Length, back.Length);
This could easily be used to implement your own version of Concat.
If you can manipulate one of the arrays, you can resize it before performing the copy:
T[] array1 = getOneArray();
T[] array2 = getAnotherArray();
int array1OriginalLength = array1.Length;
Array.Resize<T>(ref array1, array1OriginalLength + array2.Length);
Array.Copy(array2, 0, array1, array1OriginalLength, array2.Length);
Otherwise, you can make a new array
T[] array1 = getOneArray();
T[] array2 = getAnotherArray();
T[] newArray = new T[array1.Length + array2.Length];
Array.Copy(array1, newArray, array1.Length);
Array.Copy(array2, 0, newArray, array1.Length, array2.Length);
More on available Array methods on MSDN.
Use LINQ:
var arr1 = new[] { 1, 2, 3, 4, 5 };
var arr2 = new[] { 6, 7, 8, 9, 0 };
var arr = arr1.Union(arr2).ToArray();
Keep in mind, this will remove duplicates. If you want to keep duplicates, use Concat.
If you don't want to remove duplicates, then try this
Use LINQ:
var arr1 = new[] { 1, 2, 3, 4, 5 };
var arr2 = new[] { 6, 7, 8, 9, 0 };
var arr = arr1.Concat(arr2).ToArray();
First, make sure you ask yourself the question "Should I really be using an Array here"?
Unless you're building something where speed is of the utmost importance, a typed List, like List<int> is probably the way to go. The only time I ever use arrays are for byte arrays when sending stuff over the network. Other than that, I never touch them.
Easier would just be using LINQ:
var array = new string[] { "test" }.ToList();
var array1 = new string[] { "test" }.ToList();
array.AddRange(array1);
var result = array.ToArray();
First convert the arrays to lists and merge them... After that just convert the list back to an array :)
I think you can use Array.Copy for this. It takes a source index and destination index so you should be able to append the one array to the other. If you need to go more complex than just appending one to the other, this may not be the right tool for you.
Everyone has already had their say but I think this more readable than the "use as Extension method" approach:
var arr1 = new[] { 1, 2, 3, 4, 5 };
var arr2 = new[] { 6, 7, 8, 9, 0 };
var arr = Queryable.Concat(arr1, arr2).ToArray();
However it can only be used when bringing together 2 arrays.
This is what I came up with. Works for a variable number of arrays.
public static T[] ConcatArrays<T>(params T[][] args)
{
if (args == null)
throw new ArgumentNullException();
var offset = 0;
var newLength = args.Sum(arr => arr.Length);
var newArray = new T[newLength];
foreach (var arr in args)
{
Buffer.BlockCopy(arr, 0, newArray, offset, arr.Length);
offset += arr.Length;
}
return newArray;
}
...
var header = new byte[] { 0, 1, 2};
var data = new byte[] { 3, 4, 5, 6 };
var checksum = new byte[] {7, 0};
var newArray = ConcatArrays(header, data, checksum);
//output byte[9] { 0, 1, 2, 3, 4, 5, 6, 7, 0 }
Assuming the destination array has enough space, Array.Copy() will work. You might also try using a List<T> and its .AddRange() method.
Personally, I prefer my own Language Extensions, which I add or remove at will for rapid prototyping.
Following is an example for strings.
//resides in IEnumerableStringExtensions.cs
public static class IEnumerableStringExtensions
{
public static IEnumerable<string> Append(this string[] arrayInitial, string[] arrayToAppend)
{
string[] ret = new string[arrayInitial.Length + arrayToAppend.Length];
arrayInitial.CopyTo(ret, 0);
arrayToAppend.CopyTo(ret, arrayInitial.Length);
return ret;
}
}
It is much faster than LINQ and Concat. Faster still, is using a custom IEnumerable Type-wrapper which stores references/pointers of passed arrays and allows looping over the entire collection as if it were a normal array. (Useful in HPC, Graphics Processing, Graphics render...)
Your Code:
var someStringArray = new[]{"a", "b", "c"};
var someStringArray2 = new[]{"d", "e", "f"};
someStringArray.Append(someStringArray2 ); //contains a,b,c,d,e,f
For the entire code and a generics version see: https://gist.github.com/lsauer/7919764
Note: This returns an unextended IEnumerable object. To return an extended object is a bit slower.
I compiled such extensions since 2002, with a lot of credits going to helpful people on CodeProject and 'Stackoverflow'. I will release these shortly and put the link up here.
Just to have it noted as an option: if the arrays you are working with are of a primitive type – Boolean (bool), Char, SByte, Byte, Int16 (short), UInt16, Int32 (int), UInt32, Int64 (long), UInt64, IntPtr, UIntPtr, Single, or Double – then you could (or should?) try using Buffer.BlockCopy. According to the MSDN page for the Buffer class:
This class provides better performance for manipulating primitive types than similar methods in the System.Array class.
Using the C# 2.0 example from #OwenP's answer as a starting point, it would work as follows:
int[] front = { 1, 2, 3, 4 };
int[] back = { 5, 6, 7, 8 };
int[] combined = new int[front.Length + back.Length];
Buffer.BlockCopy(front, 0, combined, 0, front.Length);
Buffer.BlockCopy(back, 0, combined, front.Length, back.Length);
There is barely any difference in syntax between Buffer.BlockCopy and the Array.Copy that #OwenP used, but this should be faster (even if only slightly).
I needed a solution to combine an unknown number of arrays.
Surprised nobody else provided a solution using SelectMany with params.
private static T[] Combine<T>(params IEnumerable<T>[] items) =>
items.SelectMany(i => i).Distinct().ToArray();
If you don't want distinct items just remove distinct.
public string[] Reds = new [] { "Red", "Crimson", "TrafficLightRed" };
public string[] Greens = new [] { "Green", "LimeGreen" };
public string[] Blues = new [] { "Blue", "SkyBlue", "Navy" };
public string[] Colors = Combine(Reds, Greens, Blues);
Note: There is definitely no guarantee of ordering when using distinct.
In case someone else is looking for how to merge two image byte arrays:
private void LoadImage()
{
string src = string.empty;
byte[] mergedImageData = new byte[0];
mergedImageData = MergeTwoImageByteArrays(watermarkByteArray, backgroundImageByteArray);
src = "data:image/png;base64," + Convert.ToBase64String(mergedImageData);
MyImage.ImageUrl = src;
}
private byte[] MergeTwoImageByteArrays(byte[] imageBytes, byte[] imageBaseBytes)
{
byte[] mergedImageData = new byte[0];
using (var msBase = new MemoryStream(imageBaseBytes))
{
System.Drawing.Image imgBase = System.Drawing.Image.FromStream(msBase);
Graphics gBase = Graphics.FromImage(imgBase);
using (var msInfo = new MemoryStream(imageBytes))
{
System.Drawing.Image imgInfo = System.Drawing.Image.FromStream(msInfo);
Graphics gInfo = Graphics.FromImage(imgInfo);
gBase.DrawImage(imgInfo, new Point(0, 0));
//imgBase.Save(Server.MapPath("_____testImg.png"), ImageFormat.Png);
MemoryStream mergedImageStream = new MemoryStream();
imgBase.Save(mergedImageStream, ImageFormat.Png);
mergedImageData = mergedImageStream.ToArray();
mergedImageStream.Close();
}
}
return mergedImageData;
}
If you have the source arrays in an array itself you can use SelectMany:
var arrays = new[]{new[]{1, 2, 3}, new[]{4, 5, 6}};
var combined = arrays.SelectMany(a => a).ToArray();
foreach (var v in combined) Console.WriteLine(v);
gives
1
2
3
4
5
6
Probably this is not the fastest method but might fit depending on usecase.
Here is a simple example using Array.CopyTo.
I think that it answers your question and gives an example of CopyTo usage - I am always puzzled when I need to use this function because the help is a bit unclear - the index is the position in the destination array where inserting occurs.
int[] xSrc1 = new int[3] { 0, 1, 2 };
int[] xSrc2 = new int[5] { 3, 4, 5, 6 , 7 };
int[] xAll = new int[xSrc1.Length + xSrc2.Length];
xSrc1.CopyTo(xAll, 0);
xSrc2.CopyTo(xAll, xSrc1.Length);
I guess you can't get it much simpler.
I'm assuming you're using your own array types as opposed to the built-in .NET arrays:
public string[] merge(input1, input2)
{
string[] output = new string[input1.length + input2.length];
for(int i = 0; i < output.length; i++)
{
if (i >= input1.length)
output[i] = input2[i-input1.length];
else
output[i] = input1[i];
}
return output;
}
Another way of doing this would be using the built in ArrayList class.
public ArrayList merge(input1, input2)
{
Arraylist output = new ArrayList();
foreach(string val in input1)
output.add(val);
foreach(string val in input2)
output.add(val);
return output;
}
Both examples are C#.
int [] SouceArray1 = new int[] {2,1,3};
int [] SourceArray2 = new int[] {4,5,6};
int [] targetArray = new int [SouceArray1.Length + SourceArray2.Length];
SouceArray1.CopyTo(targetArray,0);
SourceArray2.CopyTo(targetArray,SouceArray1.Length) ;
foreach (int i in targetArray) Console.WriteLine(i + " ");
Using the above code two Arrays can be easily merged.
Created and extension method to handle null
public static class IEnumerableExtenions
{
public static IEnumerable<T> UnionIfNotNull<T>(this IEnumerable<T> list1, IEnumerable<T> list2)
{
if (list1 != null && list2 != null)
return list1.Union(list2);
else if (list1 != null)
return list1;
else if (list2 != null)
return list2;
else return null;
}
}
string[] names1 = new string[] { "Ava", "Emma", "Olivia" };
string[] names2 = new string[] { "Olivia", "Sophia", "Emma" };
List<string> arr = new List<string>(names1.Length + names2.Length);
arr.AddRange(names1);
arr.AddRange(names2);
string[] result = arr.Distinct().ToArray();
foreach(string str in result)
{
Console.WriteLine(str.ToString());
}
Console.ReadLine();
I wanted to find an approach without using any libraries or functionality beyond arrays themselves.
The first two examples are mostly for reading the logic from scratch, but I also wonder if there could be performance variations depending on the sitaution.
The third example is the most practical choice.
// Two for-loops
private static int[] MergedArrays_1(int[] a, int[] b)
{
int[] result = new int[a.Length + b.Length];
for (int i = 0; i < a.Length; i++)
{
result[i] = a[i];
}
for (int i = a.Length; i < result.Length; i++)
{
result[i] = b[i - a.Length];
}
return result;
}
// One for-loop
private static int[] MergedArrays_2(int[] a, int[] b)
{
int[] results = new int[a.Length + b.Length];
for (int i = 0; i < results.Length; i++)
{
results[i] = (i < a.Length) ? a[i] : b[i - a.Length];
}
return results;
}
// Array Method
private static int[] MergedArrays_3(int[] a, int[] b)
{
int[] results = new int[a.Length + b.Length];
a.CopyTo(results, 0);
b.CopyTo(results, a.Length);
return results;
}
Lastly, I made a fourth example, that can merge multiple arrays, using the params keyword.
int[] result = MultipleMergedArrays(arrayOne, arrayTwo, arrayThree);
private static int[] MultipleMergedArrays(params int[][] a)
{
// Get Length
int resultsLength = 0;
for (int row = 0; row < a.GetLength(0); row++)
{
resultsLength += a.Length;
}
// Initialize
int[] results = new int[resultsLength];
// Add Items
int index = 0;
for (int row = 0; row < a.GetLength(0); row++)
{
a[row].CopyTo(results, index);
index += a[row].Length;
}
return results;
}
The way it works when using params, is that the single-dimension arrays are passed into a jagged array.
GetLength(0) returns the number of arrays contained within the jagged array.
The code first counts the Length of all the arrays, then it initializes a new array based on that size, and starts adding entire arrays into the new results array by using the CopyTo() method, while adding the Length of each added array to an index counter.
PS: Some times it is necessary to remove empty items, or certain items, from arrays when merging.
private static int[] RemoveEmpty(int[] array)
{
int count = 0;
for (int i = 0; i < array.Length; i++)
{
if (array[i] == 0) count++;
}
int[] result = new int[array.Length - count];
count = 0;
for (int i = 0; i < array.Length; i++)
{
if (array[i] == 0) continue;
result[count] = array[i];
count++;
}
return result;
}
This function can be combined with the ones above.
It takes an array, counts the number of items that match zero. And creates a new array of the proper size. Then the counter is recycled and used as an index, for where to put place the input array's values into the new and smaller result array.
When an item matches zero, it skips the rest of the code in that round of the loop, and continues with the next round, without incrementing the integer counter.
Since .NET 5, we now have AllocateUnitializedArray which can possibly add an additional (small) performance improvement for the suggested solutions:
public static T[] ConcatArrays<T>(IEnumerable<T[]> arrays)
{
var result = GC.AllocateUnitializedArray<T>(arrays.Sum(a => a.Length));
var offset = 0;
foreach (var a in arrays)
{
a.CopyTo(result, offset);
offset += a.Length;
}
return result;
}
This code will work for all cases:
int[] a1 ={3,4,5,6};
int[] a2 = {4,7,9};
int i = a1.Length-1;
int j = a2.Length-1;
int resultIndex= i+j+1;
Array.Resize(ref a2, a1.Length +a2.Length);
while(resultIndex >=0)
{
if(i != 0 && j !=0)
{
if(a1[i] > a2[j])
{
a2[resultIndex--] = a[i--];
}
else
{
a2[resultIndex--] = a[j--];
}
}
else if(i>=0 && j<=0)
{
a2[resultIndex--] = a[i--];
}
else if(j>=0 && i <=0)
{
a2[resultIndex--] = a[j--];
}
}
Simple code to join multiple arrays:
string[] arr1 = ...
string[] arr2 = ...
string[] arr3 = ...
List<string> arr = new List<string>(arr1.Length + arr2.Length + arr3.Length);
arr.AddRange(arr1);
arr.AddRange(arr2);
arr.AddRange(arr3);
string[] result = arr.ToArray();
This is another way to do this :)
public static 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
}
public static void MergeArrays<T>(ref T[] tableOne, T[] tableTwo) {
foreach(var element in tableTwo) {
ArrayPush(ref tableOne, element);
}
}
Here is the snippet/example
Try this:
ArrayLIst al = new ArrayList();
al.AddRange(array_1);
al.AddRange(array_2);
al.AddRange(array_3);
array_4 = al.ToArray();