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C# decimals, money change in program and different methods or variables

I'm wondering if someone can help me with decimals? Im going to make a program there can wright price and how much you paid, and then get a change back, but i need to add decimals. The decimals have to round up or down, so if it is 0,11 it goes to 0, if it is o,20 it goes to 0,25. So it will round up to either 0,25, 0,50, 0,75 and later on 1. The change have too also show in which cash you get back, so like 100 bucks, 500 bucks, 50 bucks if you know what i mean. I dont know how to do. This is how long i come:
using System;
namespace inlämninguno
{
class Program
{
// Starting point of my "Change" program
static void Main(string[] args)
{
Console.WriteLine(Subtract()); // adding a subract variable in the beginning of the code
Console.Read();
}
// Using the double datatype to for the decimals
public static double Subtract()
{
Console.WriteLine("Price?"); // how much it costs
string number1Input = Console.ReadLine();
Console.WriteLine("Paid?"); // how much the customer pays
string number2Input = Console.ReadLine();
double prince = Convert.ToDouble(number1Input);
double paid = Convert.ToDouble(number2Input);
// This is for the subtracting part
double num1 = double.Parse(number1Input);
double num2 = double.Parse(number2Input);
double result = num2 - num1; // this is so the console subtracts the values, have to put num2 first so the output isn't negative
Console.Write("Your change is " + result + ":"); // Output "Your change is ..."
return result; // A method that gives the right output of the code
}
}
}
Can someone please help me? Im stuck :D
I tried to convert to double and lots of stuff, but I don't know how to do now.

I can't figure out why I'm reading wrong input in reading array elements in codechef problem for reverse array problem

I'm getting different user input instead of getting real inputs given by user in codechef
User Input:
4
1 2 3 4
Expected Output:
4 3 2 1
using System;
public class Test
{
public static void Main()
{
int N = Convert.ToInt32(Console.ReadLine());
int[] arr = new int[N];
for(int i=0;i<N;i++){
arr[i] = Convert.ToInt32(Console.Read());
}
for(int j=N-1;j>=0;j--){
Console.Write(arr[j]);
Console.Write(" ");
}
}
}
Output I got:
32 50 32 49

Since you said you want to do it without ReadLine, let's work with your current code. There are two issues at hand.
You should skip the spaces
You get the character codes instead of the values
To skip the spaces, you can simply read them and do nothing with the read character. I implemented this below in a way that assumes after every number (one digit long) there will be a single space to ignore. But you could also do that in a less hacky way by checking what the read character actually is before you discard it.
To get the character code into the value, I first perform a conversion into a char by casting it. Then I get the numeric value, which might be a double. But because you know that your numbers are integers, we can cast that to int.
using System;
class Program {
static void Main(string[] args) {
int N = Convert.ToInt32(Console.ReadLine());
int[] arr = new int[N];
for(int i=0;i<N;i++){
arr[i] = (int)Char.GetNumericValue((char)Console.Read());
Console.Read();
}
for(int j=N-1;j>=0;j--){
Console.Write(arr[j]);
Console.Write(" ");
}
}
}

Could someone explain why Converting to int and using read line instead of Read fixed my issue?

So previous I was having a ton of trouble with finding the difference between a randomly generated number and user input. I did a little search and found that I couldn't use Console.Read(); and that I actually had to use this int guess = Convert.ToInt32(Console.ReadLine()); While playing around with it i accidentally made it Convert.ToInt32(Console.Read()); which was in turn making the math completely wrong. Apologies if I'm not explaining myself effectively I'm new to coding and this was meant to be something to learn from. Thanks!
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApplication2
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Would you like to play the guessing game?");
string input = Console.ReadLine();
if (input.Equals("yes"))
{
Console.WriteLine("Alright! The rules are simple, i'll think of a number and you guess it!");
Console.WriteLine("Alright enter your guess: ");
int guess = Convert.ToInt32(Console.ReadLine());
Random rand = new Random();
int answer = rand.Next(1,11);
if (rand.Equals(guess))
{
Console.WriteLine("Congratulations you guessed correctly!");
}
else
{
Console.WriteLine("Aww you were so close! I guessed " + answer);
int difference = guess - answer;
Console.WriteLine("you were only " + Math.Abs(difference) + " away");
}
} else
{
Console.WriteLine("Closing application...");
Thread.Sleep(1000);
Environment.Exit(0);
}
}
}
}

Console.Read()
Returns you the ascii value of a single character being input.
For example, entering 'A' would return 65. See here for a list of ascii codes. Note that the ascii value for 1 is actually 49.
Convert.ToInt32(Console.ReadLine());
Reads the entire line and tries to convert it to an integer.

Console.Read() will grab just one character and Console.ReadLine() takes the whole line or everything the user types until it found the "Enter" key pressed.

Becuase Console.Read reads in characters from the console. It returns, as an integer. So when you enter "yes" the output will be
121 = y
101 = e
115 = s
13 =
10 =
The final two characters (13 and 10) are equal to the Windows newline.

Count Zeroes before the Decimal Point

I am trying to count how many zeroes are a before a decimal.
private void textBox1_TextChanged(object sender, EventArgs e)
{
decimal x = 0;
if (Decimal.TryParse(textBox1.Text, out x))
{
var y = 1000000;
var answer = x * y;
displayLabel2.Text = (x.ToString().Replace(".", "").TrimStart(new Char[] { '0' }) + "00").Substring(0, 2);
}
else
{
displayLabel2.Text = "error";
}
}
When I plug in (lets say) 7.2 I get an output that displays 72, which is what I want. Now I need another display. That initial 7.2 is being multiplied by 1000000. So the quotent of that would be 7,200,000.00. Now I need to some how count the 5 zeroes before the decimal point and display 5 for that. Then if I were to do .72. My Quotent would be 720,000.00. And I would need to display 4, for the 4 zeroes. And so on. Then I need to output that number to displayLabel5.Text

Here's a one line Linq you could try to count zeroes before the decimal. You can Split() first by the decimal then perform a Where().Count() to get the number of zeros.
using System;
using System.Linq;
public class Program
{
public static void Main()
{
string myString = (720000.00).ToString();
Console.WriteLine(myString.Split('.')[0].Where(d => d == '0').Count());
}
}
Results:
4
Demo

Quick and dirty code so be careful, but AFAIK this is the fastest way to do it.
// Input assuming you've sanitised it
string myInputString = "720000.00";
// Remove the decimals
myInputString = myInputString.Substring(0, myInputString.IndexOf("."));
// The count
int count = 0;
// Loop through and count occurrences
foreach (char c in myInputString)
{
if (c == "0")
{
count++;
}
}
Count is now 4.
Guarantee you this is faster than Regex ;-)
Edit: Sorry for the multiple edits, it's been a long day. Need coffee.

use a regular expression to find all the zeros before the period, then get the string length of that match.
Regex regex = new Regex(#"(0+)\.?");
string value1 = "7,200,000.00";
value1 = value1.Replace(",",""); //get rid of the commas
Match match = regex.Match(value1);
if (match.Success)
{
Console.WriteLine(match.Value.Length);
}
As always test the code because I wrote it just now here in this little text box and not in actual visual studio where I could compile and test it myself. But this should at least illustrate the methodology.
Edit:
slight tweak to the regex to account for the possibility that the number will not display a decimal point at all.

C# Variable int assumes a different value

I'm trying to create a simple program to calculate an average. The user should enter a positive number, then I create a loop to sum from 0 to the number entered. Then the average is the total divided by the number entered.
Problem: When I enter a number, for example, 10, the variable becomes 58. To any value that I enter, it always adds 48. Anyone have a clue about this issue?
Here is the code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace inClass1
{
class Loops
{
static void Main(string[] args)
{
int total = 0;
int num;
Console.Write("Enter a positive number: ");
num = Convert.ToInt32(Console.Read());
for (int i = 0; i <= num; i++)
{
total = total + i;
}
double average = total / (double)num;
Console.WriteLine("The average is = " + average);
Console.ReadLine();
}
}
}

It's because Console.Read method reads the first char and returns its ASCII value. And it only reads one char, so you can't read more than one number at the same time. To fix that just use Console.ReadLine to take a string as input:
um = Convert.ToInt32(Console.ReadLine());
In case where the user inputs an invalid number this will fail. To prevent that you can look into int.TryParse method.

The problem is that you are using Console.Read.
That method returns a int, not a string. That int is the Unicode character code of the read character. The overload of Convert.ToInt32 that takes a int looks like this:
public static int ToInt32(int value) {
return value;
}
(Reference Source)
Which means that its just returning the passed value (instead of parsing). Unicode '1' is the number 49.
Instead, use Console.ReadLine which in addition to getting the whole input (not just the first character) will return a string, so that int.Parse is called on it instead of casting when you use Convert.ToInt32.