Develop Reference

c# how to fill an array with user input

I'm creating a lottery program that users can choose from a series of numbers between a particular range and the program then creates its own version of numbers and compares those user values against the program's random numbers which any matches that the program then finds are then displayed to the user.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Assessment1.Lottery
{
internal class Program
{
static void Main(string[] args)
{
Console.WriteLine("Please insert 6 lottery numbers:");
int range = 100;
int minValue = 0;
int maxValue = 100;
int a = 0;
Random rnd = new Random();
int[] myArray = new int[6];
for ( int i=0; i < myArray.Length; i++ )
{
int randomNumber = rnd.Next(minValue, maxValue);
myArray[i] = randomNumber;
Console.WriteLine(randomNumber);
myArray[i] = int.Parse(Console.ReadLine());
Console.WriteLine(myArray[i]);
while (a < 5)
{
if (int.TryParse(Console.ReadLine(), out myArray[a]))
a++;
else
Console.WriteLine("invalid integer");
}
double arry = myArray.Average();
if(arry > 0)
Console.WriteLine("found");
else
Console.WriteLine("not found");
int BinarySearch(int[] array, int value, int low, int high)
{
if ( high >= low)
{
int mid = (low + high) / 2;
if (array[mid] == value) return mid;
if (array[mid] == value) return BinarySearch(array, value, low, mid - 1);
return BinarySearch(array, value, mid + 1, high);
}
return -1;
}
}
Console.ReadLine();
}
}
}
when I run the program it shows the following
Please insert 6 lottery numbers: 64
how can I fix this so that the array can be filled with user input

Here is a version of something I wrote a while back and modified to your parameters, if there are bugs please don't ask me to fix.
static void Main(string[] args)
{
int stop = 0;
int[] chosenNum = new int[6];
while (stop == 0)
{
Console.Clear();
string con = "";
Console.WriteLine("Enter six numbers between 1-100 separated by a comma with no duplicates:");
string numbers = Console.ReadLine();
string[] userNumbers = numbers.Replace(" ", "").Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries).ToArray();;//remove ex: ,, issues
string[] checkDup = userNumbers.Distinct().ToArray();//remove duplicates
if (userNumbers.Count() < 6)
{
Console.WriteLine("You entered less than six numbers");
Console.WriteLine("Try Again Y or N");
con = Console.ReadLine();
if (con.ToUpper() != "Y")
{
stop = 1;
}
}
else if (userNumbers.Count() > 6)
{
Console.WriteLine("You entered more than 6 numbers");
Console.WriteLine("Try Again Y or N");
con = Console.ReadLine();
if (con.ToUpper() != "Y")
{
stop = 1;
}
}
else if (checkDup.Count() < 6)
{
Console.WriteLine("You entered duplicate numbers");
Console.WriteLine("Try Again Y or N");
con = Console.ReadLine();
if (con.ToUpper() != "Y")
{
stop = 1;
}
}
else if (!isNumeric(userNumbers))
{
Console.WriteLine("You entered non-numeric value(s)");
Console.WriteLine("Try Again Y or N");
con = Console.ReadLine();
if (con.ToUpper() != "Y")
{
stop = 1;
}
}
else if (isInRange(userNumbers) < 6)
{
Console.WriteLine("You entered out of range value(s)");
Console.WriteLine("Try Again Y or N");
con = Console.ReadLine();
if (con.ToUpper() != "Y")
{
stop = 1;
}
}
else
{
var lowerBound = 1;
var upperBound = 100;
var random = new Random();
int[] randomNum = new int[6];
int count = 0;
foreach(string str in userNumbers){
var rNum = random.Next(lowerBound, upperBound);
randomNum[count] = rNum;
count++;
}
string[] ourPicks = Array.ConvertAll(randomNum, s => s.ToString()).ToArray();
Array.Sort(userNumbers);
Array.Sort(ourPicks);
//string[] ourpicks = { "1", "2" };//for testing
Console.WriteLine("Your Numbers: {0}", string.Join(", ", userNumbers));
Console.WriteLine("Our Numbers: {0}", string.Join(", ", ourPicks));
string[] result = userNumbers.Intersect(ourPicks).ToArray();
if(result.Count() > 0)
{
Console.WriteLine("Matchs: {0}", string.Join(", ", result));
}
else
{
Console.WriteLine("Match's = 0");
}
stop = 1;
}
}
Console.ReadLine();
}
public static bool isNumeric(string[] num)
{
foreach (string str in num)
{
bool check = int.TryParse(str, out int test);
if (!check)
{
return false;
}
}
return true;
}
public static int isInRange(string[] num)
{
int count = 0;
foreach (string str in num)
{
int.TryParse(str, out int test);
if (test > 0 & test <= 100)
{
count++;
}
}
return count;
}

C# Collatz - Does anyone know a fix?

Hey does anyone have a fix for this? I don't know why i keep getting an error that the main-cs and compilation fails.
using System;
class MainClass {
public static void Main (string[] args) {
Console.WriteLine ("Length of Collatz Row");
int cn = Console.ReadLine();
CollatzListLength(cn);
}
public int CollatzListLength(n){
int number;
List<int> numbers = new List<int>();
while(n != 1){
if(n % 2 == 0){
number = n/2;
}
if(n%2 ==1){
number = n*3 + 1;
}
n = number;
numbers.Add(number);
}
return numbers.Count;
}

Console.ReadLine() returns a string, not an int.
CollatzListLength needs to be static and the parameter needs to be declared as int
n = number; doesn't work because number may never be assigned a value. Use else instead of if (n % 2 == 1) as it just checks the other possible condition anyway.
In total:
static void Main(string[] args)
{
Console.WriteLine("Length of Collatz Row");
if (int.TryParse(Console.ReadLine(), out int cn))
CollatzListLength(cn);
else
Console.WriteLine("Needs a number");
}
public static int CollatzListLength(int n)
{
int number;
List<int> numbers = new List<int>();
while (n != 1)
{
if (n % 2 == 0)
{
number = n / 2;
}
else
{
number = n * 3 + 1;
}
n = number;
numbers.Add(number);
}
return numbers.Count;
}
I haven't actually checked the sanity of the code though.

An alternative, repaired to compile without error messages:
using System;
using System.Collections.Generic;
class Program
{
public static void Main(string[] args)
{
Console.WriteLine("Length of Collatz Row");
int cn = int.Parse(Console.ReadLine());
int len = CollatzListLength(cn);
Console.WriteLine($"len {len}");
}
public static int CollatzListLength(int n)
{
int number = 0;
List<int> numbers = new List<int>();
while (n != 1)
{
if (n % 2 == 0)
{
number = n / 2;
}
if (n % 2 == 1)
{
number = n * 3 + 1;
}
n = number;
numbers.Add(number);
}
return numbers.Count;
}
}

c# subtract a number from an array index in a for loop

I need to find the difference of each number value in an array from an average value. I need to loop through each value and subtract each value FROM the average and display the difference. I have tried several different ways but the difference always comes out as 0 at the end. What am i doing wrong here?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using static System.Console;
namespace AvgNDiff
{
class Program
{
static void Main(string[] args)
{
int[] numbers = new int[10];
int x = 0;
int i;
string entryString = "";
int counter = 0;
int countdown = 10;
int sum = 0;
int average = 0;
while (counter < numbers.Length && numbers[x] != 10 && entryString != "0")
{
if (x == 0)
Write("Enter up to 10 numbers or type 0 to stop > ");
else if (x == 9)
Write("Enter {0} more number or type 0 to stop > ", countdown);
else
Write("Enter up to {0} more numbers or type 0 to stop > ", countdown);
entryString = ReadLine();
numbers[x] = Convert.ToInt32(entryString);
if (entryString != "0")
{
sum += numbers[x];
counter++;
x++;
}
countdown--;
}
average = sum / x;
WriteLine("\n\nYou entered {0} numbers with a sum of {1}", x, sum);
WriteLine("The average of your numbers is " + average);
WriteLine("\n\nNumber Difference");
WriteLine("-------------------------------");
for (i=0; i < x; i++)
{
int value = numbers[i];
int diff = average-value;
WriteLine(String.Format("{0,-10} {1,-10}", (numbers[i]), diff));
}
ReadKey();
}
}
}

Take a look here
int value = numbers[i];
int diff = value - average;
WriteLine(String.Format("{0,-10} {1,-10}", (numbers[i]), value));
the key issue here is the writeline statement.
Youve told it to display numbers[i], and oh wait.. numbers[i] (as thats what value is)
yet diff contains the variance from the average...

static void Main(string[] args)
{
List<int> numberList = new List<int>();
Console.WriteLine("Enter up to 10 numbers or type 0 to stop:");
for (int i = 0; i < 10; i++)
{
int userInput = 0;
while (!int.TryParse(Console.ReadLine(), out userInput))
{
Console.WriteLine("Only integer numbers accepted, let's try again...:");
}
if (userInput == 0)
{
break;
}
else
{
numberList.Add(userInput);
if (i < 9)
{
Console.WriteLine("Yeah, {0} more number{1} to go!", (9 - i), (i == 8 ? "" : "s"));
}
}
}
double average = numberList.Average();
for (int i = 0; i < numberList.Count; i++)
{
Console.WriteLine("#{0}: {1} - {2} = {3}", (i+1), numberList[i], average, (numberList[i] - average));
}
Console.ReadLine();
}

Do not cram the entire soultion into the single Main, extract (and debug) a method:
// Subtract each item from the average
private static double[] MyNormalize(int[] source) {
double sum = 0.0;
foreach (var item in source)
sum += item;
double[] result = new double[source.Length];
for (int i = 0; i < source.Length; ++i)
result[i] = sum / source.Length - source[i];
return result;
}
...
static void Main(string[] args) {
int[] numbers = new int[10];
...
// Input
while (counter < numbers.Length && numbers[x] != 10 && entryString != "0") {
...
entryString = ReadLine();
numbers[x] = Convert.ToInt32(entryString);
}
// Business logic
double[] norm = MyNormalize(numbers);
// Output
for (int i = 0; i < numbers.Length; ++i)
WriteLine(String.Format("{0,-10} {1,-10}", numbers[i], norm[i]));
}

Number of zeroes at the end of factorial

I need to find the number of zeroes at the end of a factorial number. So here is my code, but it doesn't quite work :/
using System;
class Sum
{
static void Main(string[] args)
{
int n = int.Parse(Console.ReadLine());
long factoriel = 1;
for (int i = 1; i <= n; i++)
{
factoriel *= i;
}
Console.WriteLine(factoriel);
int timesZero = 0;
while(factoriel % 10 != 0)
{
timesZero++;
}
Console.WriteLine(timesZero);
}
}
I know I can use a for loop and divide by 5, but I don't want to. Where is the problem in my code and why isn't it working?

There's problem with your algorithm: integer overflow. Imagine, that you are given
n = 1000
and so n! = 4.0238...e2567; you should not compute n! but count its terms that are in form of (5**p)*m where p and m are some integers:
5 * m gives you one zero
25 * m gives you two zeros
625 * m gives you three zeros etc
The simplest code (which is slow on big n) is
static void Main(string[] args) {
...
int timesZero = 0;
for (int i = 5; i <= n; i += 5) {
int term = i;
while ((term % 5) == 0) {
timesZero += 1;
term /= 5;
}
}
...
}
Much faster implementation is
static void Main(string[] args) {
...
int timesZero = 0;
for (int power5 = 5; power5 <= n; power5 *= 5)
timesZero += n / power5;
...
}

Counting Trailing zeros in Factorial
static int countZerosInFactOf(int n)##
{
int result = 0;
int start = 1;
while (n >= start)
{
start *= 5;
result += (int)n/start;
}
return result;
}

Make sure to add inbuilt Reference System.Numeric
using System.Text;
using System.Threading.Tasks;
using System.Numeric
namespace TrailingZeroFromFact
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enter a no");
int no = int.Parse(Console.ReadLine());
BigInterger fact = 1;
if (no > 0)
{
for (int i = 1; i <= no; i++)
{
fact = fact * i;
}
Console.WriteLine("{0}!={1}", no, fact);
string str = fact.ToString();
string[] ss = str.Split('0');
int count = 0;
for (int i = ss.Length - 1; i >= 0; i--)
{
if (ss[i] == "")
count = count + 1;
else
break;
}
Console.WriteLine("No of trailing zeroes are = {0}", count);
}
else
{
Console.WriteLine("Can't calculate factorial of negative no");
}
Console.ReadKey();
}
}
}

static void Main(string[] args)
{
Console.WriteLine("Enter the number:");
int n = int.Parse(Console.ReadLine());
int zero = 0;
long fac=1;
for (int i = 1; i <= n; i++)
{
fac *= i;
}
Console.WriteLine("Factorial is:" + fac);
ab:
if (fac % 10 == 0)
{
fac = fac / 10;
zero++;
goto ab;
}
else
{
Console.WriteLine("Zeros are:" + zero);
}
Console.ReadLine();
}

Your code seems fine, just a little correction in the while-condition:
public static int CalculateTrailingZeroes(BigInteger bigNum)
{
int zeroesCounter = 0;
while (bigNum % 10 == 0)
{
zeroesCounter++;
bigNum /=10;
}
return zeroesCounter;
}
That works, I just tested it.

Convert integer to binary in C#

How to convert an integer number into its binary representation?
I'm using this code:
String input = "8";
String output = Convert.ToInt32(input, 2).ToString();
But it throws an exception:
Could not find any parsable digits

Your example has an integer expressed as a string. Let's say your integer was actually an integer, and you want to take the integer and convert it to a binary string.
int value = 8;
string binary = Convert.ToString(value, 2);
Which returns 1000.

Convert from any classic base to any base in C#
string number = "100";
int fromBase = 16;
int toBase = 10;
string result = Convert.ToString(Convert.ToInt32(number, fromBase), toBase);
// result == "256"
Supported bases are 2, 8, 10 and 16

Very Simple with no extra code, just input, conversion and output.
using System;
namespace _01.Decimal_to_Binary
{
class DecimalToBinary
{
static void Main(string[] args)
{
Console.Write("Decimal: ");
int decimalNumber = int.Parse(Console.ReadLine());
int remainder;
string result = string.Empty;
while (decimalNumber > 0)
{
remainder = decimalNumber % 2;
decimalNumber /= 2;
result = remainder.ToString() + result;
}
Console.WriteLine("Binary: {0}",result);
}
}
}

http://zamirsblog.blogspot.com/2011/10/convert-decimal-to-binary-in-c.html
public string DecimalToBinary(string data)
{
string result = string.Empty;
int rem = 0;
try
{
if (!IsNumeric(data))
error = "Invalid Value - This is not a numeric value";
else
{
int num = int.Parse(data);
while (num > 0)
{
rem = num % 2;
num = num / 2;
result = rem.ToString() + result;
}
}
}
catch (Exception ex)
{
error = ex.Message;
}
return result;
}

primitive way:
public string ToBinary(int n)
{
if (n < 2) return n.ToString();
var divisor = n / 2;
var remainder = n % 2;
return ToBinary(divisor) + remainder;
}

Another alternative but also inline solution using Enumerable and LINQ is:
int number = 25;
string binary = Enumerable.Range(0, (int)Math.Log(number, 2) + 1).Aggregate(string.Empty, (collected, bitshifts) => ((number >> bitshifts) & 1 ) + collected);

Convert.ToInt32(string, base) does not do base conversion into your base. It assumes that the string contains a valid number in the indicated base, and converts to base 10.
So you're getting an error because "8" is not a valid digit in base 2.
String str = "1111";
String Ans = Convert.ToInt32(str, 2).ToString();
Will show 15 (1111 base 2 = 15 base 10)
String str = "f000";
String Ans = Convert.ToInt32(str, 16).ToString();
Will show 61440.

static void convertToBinary(int n)
{
Stack<int> stack = new Stack<int>();
stack.Push(n);
// step 1 : Push the element on the stack
while (n > 1)
{
n = n / 2;
stack.Push(n);
}
// step 2 : Pop the element and print the value
foreach(var val in stack)
{
Console.Write(val % 2);
}
}

I know this answer would look similar to most of the answers already here, but I noticed just about none of them uses a for-loop. This code works, and can be considered simple, in the sense it will work without any special functions, like a ToString() with parameters, and is not too long as well. Maybe some prefer for-loops instead of just while-loop, this may be suitable for them.
public static string ByteConvert (int num)
{
int[] p = new int[8];
string pa = "";
for (int ii = 0; ii<= 7;ii = ii +1)
{
p[7-ii] = num%2;
num = num/2;
}
for (int ii = 0;ii <= 7; ii = ii + 1)
{
pa += p[ii].ToString();
}
return pa;
}

using System;
class Program
{
static void Main(string[] args) {
try {
int i = (int) Convert.ToInt64(args[0]);
Console.WriteLine("\n{0} converted to Binary is {1}\n", i, ToBinary(i));
} catch(Exception e) {
Console.WriteLine("\n{0}\n", e.Message);
}
}
public static string ToBinary(Int64 Decimal) {
// Declare a few variables we're going to need
Int64 BinaryHolder;
char[] BinaryArray;
string BinaryResult = "";
while (Decimal > 0) {
BinaryHolder = Decimal % 2;
BinaryResult += BinaryHolder;
Decimal = Decimal / 2;
}
BinaryArray = BinaryResult.ToCharArray();
Array.Reverse(BinaryArray);
BinaryResult = new string(BinaryArray);
return BinaryResult;
}
}

This function will convert integer to binary in C#:
public static string ToBinary(int N)
{
int d = N;
int q = -1;
int r = -1;
string binNumber = string.Empty;
while (q != 1)
{
r = d % 2;
q = d / 2;
d = q;
binNumber = r.ToString() + binNumber;
}
binNumber = q.ToString() + binNumber;
return binNumber;
}

class Program
{
static void Main(string[] args)
{
var #decimal = 42;
var binaryVal = ToBinary(#decimal, 2);
var binary = "101010";
var decimalVal = ToDecimal(binary, 2);
Console.WriteLine("Binary value of decimal {0} is '{1}'", #decimal, binaryVal);
Console.WriteLine("Decimal value of binary '{0}' is {1}", binary, decimalVal);
Console.WriteLine();
#decimal = 6;
binaryVal = ToBinary(#decimal, 3);
binary = "20";
decimalVal = ToDecimal(binary, 3);
Console.WriteLine("Base3 value of decimal {0} is '{1}'", #decimal, binaryVal);
Console.WriteLine("Decimal value of base3 '{0}' is {1}", binary, decimalVal);
Console.WriteLine();
#decimal = 47;
binaryVal = ToBinary(#decimal, 4);
binary = "233";
decimalVal = ToDecimal(binary, 4);
Console.WriteLine("Base4 value of decimal {0} is '{1}'", #decimal, binaryVal);
Console.WriteLine("Decimal value of base4 '{0}' is {1}", binary, decimalVal);
Console.WriteLine();
#decimal = 99;
binaryVal = ToBinary(#decimal, 5);
binary = "344";
decimalVal = ToDecimal(binary, 5);
Console.WriteLine("Base5 value of decimal {0} is '{1}'", #decimal, binaryVal);
Console.WriteLine("Decimal value of base5 '{0}' is {1}", binary, decimalVal);
Console.WriteLine();
Console.WriteLine("And so forth.. excluding after base 10 (decimal) though :)");
Console.WriteLine();
#decimal = 16;
binaryVal = ToBinary(#decimal, 11);
binary = "b";
decimalVal = ToDecimal(binary, 11);
Console.WriteLine("Hexidecimal value of decimal {0} is '{1}'", #decimal, binaryVal);
Console.WriteLine("Decimal value of Hexidecimal '{0}' is {1}", binary, decimalVal);
Console.WriteLine();
Console.WriteLine("Uh oh.. this aint right :( ... but let's cheat :P");
Console.WriteLine();
#decimal = 11;
binaryVal = Convert.ToString(#decimal, 16);
binary = "b";
decimalVal = Convert.ToInt32(binary, 16);
Console.WriteLine("Hexidecimal value of decimal {0} is '{1}'", #decimal, binaryVal);
Console.WriteLine("Decimal value of Hexidecimal '{0}' is {1}", binary, decimalVal);
Console.ReadLine();
}
static string ToBinary(decimal number, int #base)
{
var round = 0;
var reverseBinary = string.Empty;
while (number > 0)
{
var remainder = number % #base;
reverseBinary += remainder;
round = (int)(number / #base);
number = round;
}
var binaryArray = reverseBinary.ToCharArray();
Array.Reverse(binaryArray);
var binary = new string(binaryArray);
return binary;
}
static double ToDecimal(string binary, int #base)
{
var val = 0d;
if (!binary.All(char.IsNumber))
return 0d;
for (int i = 0; i < binary.Length; i++)
{
var #char = Convert.ToDouble(binary[i].ToString());
var pow = (binary.Length - 1) - i;
val += Math.Pow(#base, pow) * #char;
}
return val;
}
}
Learning sources:
Everything you need to know about binary
including algorithm to convert decimal to binary

class Program{
static void Main(string[] args){
try{
int i = (int)Convert.ToInt64(args[0]);
Console.WriteLine("\n{0} converted to Binary is {1}\n",i,ToBinary(i));
}catch(Exception e){
Console.WriteLine("\n{0}\n",e.Message);
}
}//end Main
public static string ToBinary(Int64 Decimal)
{
// Declare a few variables we're going to need
Int64 BinaryHolder;
char[] BinaryArray;
string BinaryResult = "";
while (Decimal > 0)
{
BinaryHolder = Decimal % 2;
BinaryResult += BinaryHolder;
Decimal = Decimal / 2;
}
// The algoritm gives us the binary number in reverse order (mirrored)
// We store it in an array so that we can reverse it back to normal
BinaryArray = BinaryResult.ToCharArray();
Array.Reverse(BinaryArray);
BinaryResult = new string(BinaryArray);
return BinaryResult;
}
}//end class Program

BCL provided Convert.ToString(n, 2) is good, but in case you need an alternate implementation which is few ticks faster than BCL provided one.
Following custom implementation works for all integers(-ve and +ve).
Original source taken from https://davidsekar.com/algorithms/csharp-program-to-convert-decimal-to-binary
static string ToBinary(int n)
{
int j = 0;
char[] output = new char[32];
if (n == 0)
output[j++] = '0';
else
{
int checkBit = 1 << 30;
bool skipInitialZeros = true;
// Check the sign bit separately, as 1<<31 will cause
// +ve integer overflow
if ((n & int.MinValue) == int.MinValue)
{
output[j++] = '1';
skipInitialZeros = false;
}
for (int i = 0; i < 31; i++, checkBit >>= 1)
{
if ((n & checkBit) == 0)
{
if (skipInitialZeros)
continue;
else
output[j++] = '0';
}
else
{
skipInitialZeros = false;
output[j++] = '1';
}
}
}
return new string(output, 0, j);
}
Above code is my implementation. So, I'm eager to hear any feedback :)

// I use this function
public static string ToBinary(long number)
{
string digit = Convert.ToString(number % 2);
if (number >= 2)
{
long remaining = number / 2;
string remainingString = ToBinary(remaining);
return remainingString + digit;
}
return digit;
}

static void Main(string[] args)
{
Console.WriteLine("Enter number for converting to binary numerical system!");
int num = Convert.ToInt32(Console.ReadLine());
int[] arr = new int[16];
//for positive integers
if (num > 0)
{
for (int i = 0; i < 16; i++)
{
if (num > 0)
{
if ((num % 2) == 0)
{
num = num / 2;
arr[16 - (i + 1)] = 0;
}
else if ((num % 2) != 0)
{
num = num / 2;
arr[16 - (i + 1)] = 1;
}
}
}
for (int y = 0; y < 16; y++)
{
Console.Write(arr[y]);
}
Console.ReadLine();
}
//for negative integers
else if (num < 0)
{
num = (num + 1) * -1;
for (int i = 0; i < 16; i++)
{
if (num > 0)
{
if ((num % 2) == 0)
{
num = num / 2;
arr[16 - (i + 1)] = 0;
}
else if ((num % 2) != 0)
{
num = num / 2;
arr[16 - (i + 1)] = 1;
}
}
}
for (int y = 0; y < 16; y++)
{
if (arr[y] != 0)
{
arr[y] = 0;
}
else
{
arr[y] = 1;
}
Console.Write(arr[y]);
}
Console.ReadLine();
}
}

This might be helpful if you want a concise function that you can call from your main method, inside your class. You may still need to call int.Parse(toBinary(someint)) if you require a number instead of a string but I find this method work pretty well. Additionally, this can be adjusted to use a for loop instead of a do-while if you'd prefer.
public static string toBinary(int base10)
{
string binary = "";
do {
binary = (base10 % 2) + binary;
base10 /= 2;
}
while (base10 > 0);
return binary;
}
toBinary(10) returns the string "1010".

I came across this problem in a coding challenge where you have to convert 32 digit decimal to binary and find the possible combination of the substring.
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Numerics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApp2
{
class Program
{
public static void Main()
{
int numberofinputs = int.Parse(Console.ReadLine());
List<BigInteger> inputdecimal = new List<BigInteger>();
List<string> outputBinary = new List<string>();
for (int i = 0; i < numberofinputs; i++)
{
inputdecimal.Add(BigInteger.Parse(Console.ReadLine(), CultureInfo.InvariantCulture));
}
//processing begins
foreach (var n in inputdecimal)
{
string binary = (binaryconveter(n));
subString(binary, binary.Length);
}
foreach (var item in outputBinary)
{
Console.WriteLine(item);
}
string binaryconveter(BigInteger n)
{
int i;
StringBuilder output = new StringBuilder();
for (i = 0; n > 0; i++)
{
output = output.Append(n % 2);
n = n / 2;
}
return output.ToString();
}
void subString(string str, int n)
{
int zeroodds = 0;
int oneodds = 0;
for (int len = 1; len <= n; len++)
{
for (int i = 0; i <= n - len; i++)
{
int j = i + len - 1;
string substring = "";
for (int k = i; k <= j; k++)
{
substring = String.Concat(substring, str[k]);
}
var resultofstringanalysis = stringanalysis(substring);
if (resultofstringanalysis.Equals("both are odd"))
{
++zeroodds;
++oneodds;
}
else if (resultofstringanalysis.Equals("zeroes are odd"))
{
++zeroodds;
}
else if (resultofstringanalysis.Equals("ones are odd"))
{
++oneodds;
}
}
}
string outputtest = String.Concat(zeroodds.ToString(), ' ', oneodds.ToString());
outputBinary.Add(outputtest);
}
string stringanalysis(string str)
{
int n = str.Length;
int nofZeros = 0;
int nofOnes = 0;
for (int i = 0; i < n; i++)
{
if (str[i] == '0')
{
++nofZeros;
}
if (str[i] == '1')
{
++nofOnes;
}
}
if ((nofZeros != 0 && nofZeros % 2 != 0) && (nofOnes != 0 && nofOnes % 2 != 0))
{
return "both are odd";
}
else if (nofZeros != 0 && nofZeros % 2 != 0)
{
return "zeroes are odd";
}
else if (nofOnes != 0 && nofOnes % 2 != 0)
{
return "ones are odd";
}
else
{
return "nothing";
}
}
Console.ReadKey();
}
}
}

int x=550;
string s=" ";
string y=" ";
while (x>0)
{
s += x%2;
x=x/2;
}
Console.WriteLine(Reverse(s));
}
public static string Reverse( string s )
{
char[] charArray = s.ToCharArray();
Array.Reverse( charArray );
return new string( charArray );
}

This was a interesting read i was looking for a quick copy paste.
I knew i had done this before long ago with bitmath differently.
Here was my take on it.
// i had this as a extension method in a static class (this int inValue);
public static string ToBinaryString(int inValue)
{
string result = "";
for (int bitIndexToTest = 0; bitIndexToTest < 32; bitIndexToTest++)
result += ((inValue & (1 << (bitIndexToTest))) > 0) ? '1' : '0';
return result;
}
You could stick spacing in there with a bit of modulos in the loop.
// little bit of spacing
if (((bitIndexToTest + 1) % spaceEvery) == 0)
result += ' ';
You could probably use or pass in a stringbuilder and append or index directly to avoid deallocations and also get around the use of += this way;

var b = Convert.ToString(i,2).PadLeft(32,'0').ToCharArray().Reverse().ToArray();

Just one line for 8 bit
Console.WriteLine(Convert.ToString(n, 2).PadLeft(8, '0'));
where n is the number