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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(" ");
}
}
}

How to create an array length based on users input

So I am currently pretty confused (keep in mind im new to coding).
I am currently trying to create a program which creates allows the user to input the amount of numbers they would like to enter in the array (it then creates an array based on that length), asks the user to input the numbers into their desired position.
My code currently looks like this:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Arrays
{
class Program
{
static void Main(string[] args)
{
//Variables
int[] array1 = new int[0];
int TotalArray, position, Number;
//Main Program
Console.WriteLine("Hello, welcome to creating your own array!");
Console.WriteLine("How many numbers do you wish to add to the array?: ");
TotalArray = int.Parse(Console.ReadLine());
Console.ReadKey();
{
Console.WriteLine("What position would you like to add your number to?: ");
position = int.Parse(Console.ReadLine());
if (position < TotalArray)
{
Console.WriteLine("What number would you like to add to position " + position);
Number = int.Parse(Console.ReadLine());
array1[position] = Number;
Console.WriteLine("Testing: " + array1[position]);
Console.ReadKey();
}
else
{
Console.WriteLine("Error! You entered your position higher than your total array!");
}
}
}
}
}
However, I do not understand how to create an array length based on the users input.
I have to tried to do this:
Console.WriteLine("Hello, welcome to creating your own array!");
Console.WriteLine("How many numbers do you wish to add to the array?: ");
TotalArray = int.Parse(Console.ReadLine());
int i = Convert.ToInt32(TotalArray);
int[] array1 = new int[i];
But get this error:
A local variable or function named 'array1' is already defined in this scope
I don't really understand what this piece of code does:
int i = Convert.ToInt32(TotalArray);
int[] array1 = new int[i];
However, I saw it mentioned on stackoverflow and thought id try an implement it. I kinda understand the 2nd line but don't really get the whole converting thing.
Any help would greatly be appreciated!

First, you don't need to convert TotalArray to an integer, since you already parsed the user's repsonse as an integer. So omit i. Next, you're declaring a new array1. Instead, just assign a new one to the same reference:
array1 = new int[TotalArray];
As for the loop. Here's the naive version, but if you need to scold the user for picking the same position twice, you'll need to do a lot more work.
int requestCount = TotalArray;
while (requestCount > 0)
{
requestCount = requestCount - 1;
Console.WriteLine("What position would you like to add your number to? (0 - "
+ (TotalArray - 1) + "): ");
position = int.Parse(Console.ReadLine());
if (position < TotalArray)
{
Console.WriteLine("What number would you like to add to position " + position);
Number = int.Parse(Console.ReadLine());
array1[position] = Number;
Console.WriteLine("Testing: " + array1[position]);
Console.ReadKey();
}
else
{
Console.WriteLine("Error! You entered your position higher than your total array!");
}
}

first this is the right way to write your code
Console.WriteLine("Hello, welcome to creating your own array!");
Console.WriteLine("How many numbers do you wish to add to the array?: ");
TotalArray = int.Parse(Console.ReadLine());
array1 = new int[TotalArray];
the third line means read the last line entered into the console then convert it to a value of type int, then store this value in the variable TotalArray
while the fourth line means construct a new array of length TotalArray then store the resulted array into the variable array1
this doesn't work when you write int[] array1 = new int[i]; because it means create a new variable called array1 then create a new array of length i to be stored in the newly created variable array1
and as you can see in your code you've already defined array1
here:
//Variables
int[] array1 = new int[0];
this is why you get the message: A local variable or function named 'array1' is already defined in this scope
but good job for a beginner.

How do I store my numbers into an array?

In my code, I am trying to generate 5 numbers. If any of the numbers equal to 4, then I want to store that 4 into an array. Currently I'm having trouble and my code will not store the 4 into the array.
static void Main()
{
Random rand = new Random();
int total = 0, randInt;
Console.WriteLine("The computer is now rolling their dice...");
int[] fours = new int[total];
for (int i = 0; i < 5; i++)
{
randInt = rand.Next(10);
Console.WriteLine("The computer rolls a {0:F0}", randInt);
if (randInt == 4)
{
total +=fours[i]; //Here I am trying to store the 4 into the array of 'fours'.
}
}
Console.WriteLine(total); //This currently prints to 0, regardless of any 4's the random number generator has generated. I want this to print out how many 4's I have rolled.
Console.ReadLine();
}

This:
total +=fours[i]
Will attempt to increment total with the int found at index i of your array (which will currently be 0, because int defaults to 0).
This:
fours[i] = 4;
Is how you assign 4 to the ith index in your array.
Read about how the assignment operator works in C#
The = operator is called the simple assignment operator. It assigns the value of the right operand to the variable, property, or indexer element given by the left operand.

How to Display the Largest and Smallest Values of an Array

To start this is a homework assignment and I'm having a bit of trouble and would like some suggestions. So far I've created this application to take 10 inputted values from a user and store them into an array. I pass the array to the SmallAndLarge method where it displays derermines the smallest and largest of the 10 values using Sort() but now i have to display the smallest and largest of the 10 values the user entered and am having a trouble. Any help at all would be great!!
Also one other problem ive noticed that if the values 1 through 10 are entered 10 will be before 2 and after one when the array is sorted and displayed. Why is this?
namespace SmallAndLarge
{
class Program
{
static void Main()
{
int found = 0;
string[] numbers = new string[10];
for (int i = 0; i < numbers.Length; i++)
{
Console.Write("Enter ten numbers --> ");
numbers[i] = Console.ReadLine();
}
SmallestAndLargest(numbers);
}
public static int SmallestAndLargest(string[] numbers1)
{
int x;
Array.Sort(numbers1);
for (x = 0; x < numbers1.Length; ++x)
Console.Write("{0} ", numbers1[x]);
return x;
}
}
}

You can use Linq to cast and return the Largest/Smallest using Min/Max
string[] numbers = new string[] {"1","2","3","15","30","7" };
var converted = numbers.Select(int.Parse);
int largest = converted.Max();
int smallest = converted.Min();

You have the numbers as strings. That explains why "10" comes before "2", it's for the same reason that "am" comes before "i" in an alphabetic sort. The first character of "10" is '1' which comes before '2'.
So before you sort the array, or search for the max og min value, you need to convert the strings into some numeric type. It could be the int type, for example. You would hold them in an array of type int[], not string[].
To convert from the string given by Console.ReadLine into int, use an overload of int.Parse or int.TryParse methods, for example.
If the user should be allowed to type non-integral numbers like 3.14, you could use decimal instead of int.

It looks like you are iterating over the array. I would do the following:
Create two int variables (small and large, respectively)
Set them both equal to the first element of the array
Loop through the elements;
For each element[i], (convert the element to int using int.Parse() or equivalent).
if element[i] > large, large = element[i]; if element[i] < small, small = element[i]
There is no need for sort if you only need min and max. And I would store the ints into and int array rather than string array, make the conversion when the user inputs the value. That way, when an invalid value is input, your program fails right then.

Here's a very simple, though long winded answer. Add the values to a List and use Min/Max returns. Your already using a for loop to iterate through the list, no reason to do it twice.
static void Main(string[] args)
{
string[] StringValues = new string[] { "1", "2", "3", "4", "5", "6", "7", "8", "9", "10","Not Number" };
List<int> ConvertedStrings = new List<int>();
foreach (string S in StringValues)
{
ConvertedStrings = ParseStringToInt(S, ConvertedStrings);
}
Console.WriteLine();
Console.WriteLine("Max Value: " + ConvertedStrings.Max().ToString());
Console.WriteLine("Min Value: " + ConvertedStrings.Min().ToString());
Console.ReadLine();
}
static private List<int> ParseStringToInt(string Input, List<int> ConvertedStrings)
{
int ConvertedValue = 0;
if (int.TryParse(Input, out ConvertedValue))
{
Console.WriteLine(Input + " sucessfully parsed and added...");
ConvertedStrings.Add(ConvertedValue);
return ConvertedStrings;
}
else
{
Console.WriteLine(Input + " failed to parse...");
}
return ConvertedStrings;
}
sa_ddam213 has got the killer answer though :P

Get the sum of an array in C# but receiving int32 error

In general, I know that int32 errors mean that a string value is not getting converted for the console program. I have seen a lot of code trying to find the answer to this including the following stackoverflow questions (seen much more but these were most useful:
How to sum up an array of integers in C#
Error CS1501: I'm not overloading a Sum() method correctly
CS0019 Operator cannot be applied to operands of type 'bool' and 'int'
That being said, this is also a homework assignment, titled UsingSum.cs as seen in a couple of these links. The difference in mine and these is that I am trying to make it so that the user enters however many Integers they want, then they are added up. The entire assignment is written in link 2....
The problem: I keep getting either 0 or System.Int32[] instead of the sum, despite the changes I make.
I cannot use Linq.
Here is the code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace UsingSum
{
class Program
{
static void Main(string[] args)
{
int i;
int usrInput;
bool running = true;
//Enter Question Asking Loop w/ running=true
while (running)
{
Console.Write("Enter a number or enter 999 to exit: ");
int[] array1 = new int[0];
for (i = 0; i < array1.Length; i++)
{
usrInput = Convert.ToInt32(Console.ReadLine());
array1[i] = Convert.ToInt32(usrInput);
}
for (i = 0; i < array1.Length; i++)
{
Console.WriteLine(array1[i]);
}
/*If the user enters 999, calls Sum() and asks user to press any key to exit.
changes 'running' from true to false to exit the question loop*/
int exit = Convert.ToInt32 (Console.ReadLine());
if (exit == 999)
{
running = false;
Sum(array1);
}
}
//Loop complete
Console.WriteLine("Press any key to exit.");
Console.ReadLine();
}
public static void Sum(int[] numbers)
{
int [] sum1 = new int [0];
int sum2 = 0;
//Program accepts user responses with or w/o this loop...Int.32 error present both ways
//for (int a = 0; a < numbers.Length; ++a)
//sum1[a] = a;
//additional loop tried w/o the loop above/below;
//when used in the WriteLine w/ sum2 it displays 0, when used with sum1 or numbers Int.32 error
//Array.ForEach(sum1, delegate(int i) { sum2 += i; });
foreach (int i in numbers)
sum2 =+ i;
Console.WriteLine("The sum of the values in your array is: " + sum1);
/*tried changing 'numbers' to sum1, sum2, sum1.Convert.ToString(),sum2.Convert.ToString()
numbers.Convert.ToString(), also tried converting sum2 to a string.*/
}
}
}
Here is my final solution!
static void Main(string[] args)
{
AskUserForNumbers();
Console.WriteLine("Press any key to exit");
Console.ReadLine();
}
public static List<Int32> AskUserForNumbers()
{
bool running = true;
List<int> numbers = new List<int>();
while (running)
{
Console.Write("Enter a number or enter 999 to exit: ");
int inputValue;
var inputString = Console.ReadLine();
//Check for "999" which indicates we should display the numbers entered, the total and then exit our loop.
if (inputString == "999")
{
Console.WriteLine("The sum of the values in your array is: " + numbers.Sum());
running = false;
}
else if (Int32.TryParse(inputString, out inputValue) && inputValue > 0)
{
numbers.Add(inputValue);
}
else
{
Console.WriteLine("Please enter a whole number greater than 0");
}
}
return numbers;
}
}
}

A few problems:
First, you're always declaring your arrays as int[] array1 = new int[0];. This means that your code for actually getting the user input will never hit. Maybe you should try using a different collection type (List<int> maybe).
Second, you never perform any error checking when parsing the integer. That's bad practice. You should be using int.TryParse(string input, out result) to verify it was a valid number before adding it to the array.
Third, you are looping over the length of the array for inputs, meaning you will loop through however long the array is, and will continue doing so until the last input you have is the exit number (999).
Fourth, the input you get for the exit code is discarded (not added to the array to sum).
Just remember that programming is very procedural. There should be clear (logical) steps from point a to point b. In fact, imagine you are the program and you're asking a friend to give you numbers to sum up for him. Give him whatever information you think might be useful (such as the exit condition). Diagram the steps, and then try to translate that to code.
Edit: The main point is that an array (which has a fixed size) is NOT the tool for the job here. You're not actually filling the array with any data, so that's why the sum never happens. The culprit is here:
int[] array1 = new int[0]; // Instantiate a zero-length array? Can't hold any values
// Will never hit inside the loop here, because i < array1.Length (which is zero) will always be false.
for (i = 0; i < array1.Length; i++)
You need to either increase the size of the array to begin with (and either reuse the indexes or resize the array) or use an non-fixed collection (List, for example). Finally, when you pass array1 to the Sum method, array1 is empty because you declared it as a zero element array. That is why you always get a zero printing out. Like I said before, imagine you are the program, and actually run through all these steps, LINE BY LINE.
For example, you start in the loop. You prepare a miniature notebook to write down all the numbers your friend is telling you with no pages in it. For every page (and realize there are none) in the notebook, you ask your friend for a number. After you've gone through every page, you now go through every page again to read all the values he gave you (keep in mind he couldn't give you any numbers, since the notebook was empty). Then you ask him one more time for a number, and if it's 999 you tell him you're done and give him the sum of all the numbers you wrote down. If he didn't give you 999 as the number, you repeat the cycle.
Do you understand WHY it's not working now?

public static void Sum(int[] numbers)
{
int sum2 = 0;
foreach (int i in numbers)
sum2 =+ i;
Console.WriteLine("The sum of the values in your array is: " + sum2);
}

foreach (int i in numbers)
sum2 =+ i;
should become
foreach (int i in numbers)
sum2 += i;

Your problem is with your first for loop. You never will add items to your array because your
for (i = 0; i < array1.Length; i++)
Since you only add to your array1 array when you enter the loop, it won't ever increment. Since i = 0 and the array1.Length is 0 to start, i will never be less than the length.
Here is what I would suggest you do.
private static void Main(string[] args) {
var running = true;
var numbers = new List<int>();
//Enter Question Asking Loop w/ running=true
while (running) {
Console.Write("Enter a number or enter 999 to exit: ");
int inputValue;
var inputString = Console.ReadLine();
//Check for "999" which indicates we should display the numbers entered, the total and then exit our loop.
if (inputString == "999") {
//Display the numbers entered
foreach (var number in numbers) {
Console.WriteLine(number);
}
Console.WriteLine("The sum of the values in your array is: " + numbers.Sum());
running = false;
}
else if (Int32.TryParse(inputString, out inputValue) && inputValue > 0) {
//We have valid input, append it to our collection
numbers.Add(inputValue);
}
else {
//The user entered invalid data. Let them know.
Console.WriteLine("Please enter a whole number greater than 0");
}
}
//Loop complete
Console.WriteLine("Press any key to exit.");
Console.ReadLine();
}

You have several small mistakes here.
In your Sum method you are no longer using the array sum1, you're summing the values into sum2, but you're printing sum1. Your sum method should be (as described by Wiktor):
public static void Sum(int[] numbers)
{
int sum2 = 0;
foreach (int i in numbers)
sum2 += i;
Console.WriteLine("The sum of the values in your array is: " + sum2);
}
Also note that you used sum2 =+ i rather than sum2 =+ i. What that's saying is "set sum2 to be equal to the positive value of i" rather than, "add i to sum2.
Next, you have some issues in how you gather your input from the user. First off, arrays don't have a mutable size. The size that they have is fixed when they are created, and the array that you create to hold onto the values to sum up from the users is initialized to a size of 0. (int[] array1 = new int[0];) If you want to get a fixed number of values from the user you can put something other than 0 there for the array size, but based on the context it appears that you want the users to be able to add values until they enter 999 at which point you end. Since you don't know the size before hand you'll want to use a List<int> rather than an array, as you can just add items to it and it will magically grow to support the new items.
I would also suggest making a new method to get all of the values from the user, rather than embedding it in your Main method.
public static List<int> AskUserForNumbers()
{
List<int> numbers = new List<int>();
while(...)//todo determine end condition
{
string userInput = Console.ReadLine();
if(...)//todo determine if user is done
{
}
else
{
int nextNumber = ...;//todo parse user input
numbers.Add(nextNumber);
}
}
return numbers;
}
I'm not sure if it's a requirement for you to stop asking for numbers when the user enters 999 or if that's just what you did. if you have a choice, I would suggest using something different such as a blank line, 0, "quit", "exit", etc. 999 is a number that someone might want to sum.
As mentioned by SPFiredrake, it's best to use int.TryParse() to parse user input, that way if they enter a number that's not an int it won't crash, and you can tell the user that it was no good and they need to try again.