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Entering elements into an array and checking to see if the element already exists [duplicate]

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Check if a value is in an array (C#)
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I'm working on a problem and i've tried it every way I can think of with a for loop but i can't figure out how to make it work as I only started on c# and programming as a whole a few weeks ago.
Write an app that inputs five numbers. As each number is read search the array if the number doesn’t exist in the array output the word “new” and insert the number into the array. If the number does exist in the array output “exists”. Once all five numbers have been entered output the content of the array.
This is what I have so far. Thanks for any help
using System;
public class Program
{
// Main method begins execution of C# application
public static void Main(string[] args)
{
int[] array = new int[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
array[i] = Convert.ToInt32(Console.ReadLine());
for (int a = 0; a < 5; a++)
{
if (array[i] != array[a])
{
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("new\n");
}
}
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("exists\n");
}
Console.WriteLine(array);
Console.ReadKey();
}
} // end class

First of all try thinking about a solution before you actually start writing some code, couple of hints
You expect some user input, we will use a variable to save the user input
You need to validate that the values does not exist in you array or structure, this can be done using the Contains method.
If it exists we continue to the next user input and print the required message.
If the value does not exists we add the value and print the new message
We will do this until the Count of the structure is equal to 5.
for reference use this While loop, Hashset.Contains and Hashset
try this:
var numbers = new HashSet<int>();
while(numbers.Count < 5)
{
Console.WriteLine("Enter a number:"); //1.
var number = Convert.ToInt32(Console.ReadLine());
if (numbers.Contains(number)) // 2.
{
Console.WriteLine("exists\n"); //3.
continue;
}
Console.WriteLine("new\n"); //4.
numbers.Add(number);
}
foreach (var n in numbers)
{
Console.WriteLine(n);
}

Use .Any() in System.Linq. Also, you don't need to continuously grab user input in your loop:
using System;
using System.Linq;
public class Program
{
// Main method begins execution of C# application
public static void Main(string[] args)
{
int[] array = new int[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
// Get user input and convert to integer:
int input = Convert.ToInt32(Console.ReadLine());
// Check if given input is already in the array:
if (! array.Any(number => number == input))
{
array[i] = input;
Console.WriteLine("new\n");
}
else
{
Console.WriteLine("exists\n");
}
}
// Print the contents of array separated by ','
Console.WriteLine(string.Join(", ", array));
Console.ReadKey();
}
}
Edit: Another variant if you want the user to fill the array completely:
using System;
using System.Linq;
public class Program
{
public static void Main(string[] args)
{
// Btw, if this is not an array of nullables,
// we will not be able to insert a zero later, as
// we will treat them as duplicates.
int?[] array = new int?[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
int input = 0;
bool duplicateAttempt = false;
do {
// Get and convert the input.
input = Convert.ToInt32(Console.ReadLine());
// See if this number is already in.
duplicateAttempt = array.Contains(input);
// Report if we attempt to insert a duplicate.
if (duplicateAttempt) Console.WriteLine("exists");
}
while (duplicateAttempt); // Keep asking while we don't get a unique number.
array[i] = input; // Store the number
Console.WriteLine("new");
}
// Print the contents of array separated by ','
Console.WriteLine(string.Join(", ", array));
Console.ReadKey();
}
}

A couple of issues with your code. You should only increment the array index if successful - otherwise the missing values will be zero. It's also a good idea to validate the input in case the user entered an invalid value. You can use linq to check if the value already exists in the array:
Here's an example:
static void Main(string[] args)
{
int[] array = new int[5];
var index = 0;
while (index < array.Length)
{
Console.WriteLine("Enter a number:");
var input = Console.ReadLine();
var value = 0;
if (!int.TryParse(input, out value))
{
Console.WriteLine("Error - value entered was not a number");
}
else
{
var match = array.Where(a => a == value);
if (match.Any())
{
Console.WriteLine("exists\n");
}
else
{
array[index] = value;
Console.WriteLine("new\n");
index++;
}
}
}
foreach (var item in array)
{
Console.WriteLine(item);
}
Console.ReadKey();
}

This appears to be a homework question, so I think it's more helpful to explain what you've done wrong and tell you what you should do...
It won't help you learn to copy and paste other people's answers.
using System;
public class Program
{
// Main method begins execution of C# application
public static void Main(string[] args)
{
int[] array = new int[5];
for (int i = 0; i < array.Length; i++)
{
Console.WriteLine("Enter a number:");
// you are putting the value into your array here. so it will always 'exist' below
array[i] = Convert.ToInt32(Console.ReadLine());
// you need to do this check before you insert the number into the array
// put the ReadLine into a variable, not directly into the array.
// then check if it's in the array already
for (int a = 0; a < 5; a++)
{
if (array[i] != array[a])
{
// here you are trying to read another value from the user.
// Console.ReadLine() will always wait for user input
// use the variable from above. but only after you have looped through all the items.
// and verified that it is not present
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("new\n");
}
}
// this is the third time you have assigned the number to the array
// and the third time you've asked for user input per loop
array[i] = int.Parse(Console.ReadLine());
Console.WriteLine("exists\n");
}
Console.WriteLine(array);
Console.ReadKey();
}
} // end class
To summarize:
you need a for loop that runs 5 times.
The for loop will do the following:
assign the user input to a variable
loop through your array (second loop) and see if it contains this variable
if the number is found, set a boolean to true. (found)
if after the loop is over, found = false, then print false
also add the number to the array (at the index of the outer loop is fine)

int not what I try and assign it

I am learning C# and having an issue understanding why my highNumber value is being displayed as 56 when running my code snippet.
//Write a program and ask the user to enter a series of numbers separated by comma. Find the maximum of the numbers
//and display it on the console. For example, if the user enters “5, 3, 8, 1, 4", the program should display 8
int highNumber = 0;
Console.Write("Enter a series of numbers separated by comma: ");
var userInput = Console.ReadLine();
for (var i = 0; i < userInput.Length; i++)
{
if (char.IsNumber(userInput[i]) == true)
{
if (userInput[i] > highNumber)
{
highNumber = Convert.ToInt32(userInput[i]);
}
}
}
Console.WriteLine("The largest number is {0}", Convert.ToInt32(highNumber));

You've entered the ASCII character '8', which has the numeric value 56.
If it's a single digit character then convert it with this
int val = (int)Char.GetNumericValue(userInput[i]);
If it's a numeric string then convert it in one call with this
int val;
bool success = Int32.TryParse(userInput, out val);
or
int val = System.Convert.ToInt32(userInput);

The LordWilmore`s answer is somehow correct if you dont use numbers greater than 10 but you can simplify and make it more accurate as below:
int highNumber = 0;
int valueTemp;
Console.Write("Enter a series of numbers separated by comma: ");
var userInput = Console.ReadLine();
string[] array = userInput.Split(',');
for (var i = 0; i < array.Length; i++)
{
if (int.TryParse(array[i], out valueTemp))
{
if (valueTemp > highNumber)
{
highNumber = valueTemp;
}
}
}
Console.WriteLine("The largest number is {0}", highNumber);
or using Max() function if you have knowledge about the List<> in c#:
int valueTemp;
Console.Write("Enter a series of numbers separated by comma: ");
var userInput = Console.ReadLine();
string[] array = userInput.Split(',');
List<int> intList = new List<int>();
for (var i = 0; i < array.Length; i++)
{
if (int.TryParse(array[i], out valueTemp))
{
intList.Add(valueTemp);
}
}
Console.WriteLine("The largest number is {0}", intList.Max());
This is a more accurate example because if put 3,33,4 in your example it will fail since you get each character and not values separated by comma. In my case I split them into pieces accordingly and then continue to test them appropriately.

Console.ReadLine(); returns a string. When you use the indexer ([i]) on the string you get individual characters, not strings or numbers. What you want is to Split the string by the commas, then use TryParse to ensure that each string is a number:
string userInput = Console.ReadLine();
string[] parts = userInput.Split(',');
for (var i = 0; i < parts.Length; i++)
{
int number;
if (int.TryParse(parts[i], out number))
{
if (number > highNumber)
{
highNumber = number;
}
}
}

Store a 2-D string array but display a 1-D string array

I'm a relatively new student to C# programming and I'm having a lot of trouble with 2-D arrays. In this program the user is supposed to input names, verbs, and objects for an insult generator, but the problem is that I have to pointlessly store them all in one 2-D string array and generate the insults in a 1-D string array and I'm just completely lost. Can I store name, verb, and object into a single 2-D string array? Any help would be appreciated.
My issue is with initializing and storing the 2D string array and then converting to the 1D array.
private static void Generate(int insultnum, int sentnum)
{
int Ncounter = 1;
int Vcounter = 1;
int Ocounter = 1;
string[,] name = new string[sentnum,?];
string[,] verb = new string[sentnum,?];
string[,] insult = new string[sentnum,?];
do
{
Console.Write("Please enter name of #{0}: ", Ncounter);
//length and height 2D array for loop text is just a placeholder from an earlier project
for (int i = 0; i < length; i++)
{
for (int j = 0; j < height; j++)
{
name[Ncounter - 1, ??] = Console.ReadLine();
}
}
//
Ncounter++;
} while (Ncounter < sentnum);
do
{
Console.Write("Please enter name of #{0}: ", Vcounter);
verb[Vcounter-1, ?] = Console.ReadLine();
//2D array loop text
Vcounter++;
} while (Vcounter < sentnum);
do
{
Console.Write("Please enter name of #{0}: ", Ocounter);
insult[Ocounter-1, ?] = Console.ReadLine();
//2D array loop text
Ocounter++;
} while (Ocounter < sentnum);
Ncounter = 0;
Vcounter = 0;
Ocounter = 0;
string[] insults = new string[insultnum];
//insults = name[?,?] + " " + verb[?,?] + " " + object[?,?];
}
Example Output:
Enter the number of insults to generate: 3
Enter the number of names, verbs, and objects: 3
Please enter name #1: Bob
Please enter name #2: Rhys
Please enter name #3: Kaa
Please enter verb #1: licks
Please enter verb #2: touches
Please enter verb #3: tastes
Please enter object #1: dirt
Please enter object #2: cars
Please enter object #3: asphalt
Insults have been generated
Kaa licks dirt
Bob tastes asphalt
Bob licks cars

2D array i.e. string[,] is a bit strange collection to store the data, since it requires that
NameCounter == VerbCounter == ObjectCounter
More natural choice is a jagged array string[][] which allows arbitrary NameCounter, VerbCounter, ObjectCounter. And, please, decompose your solution, split it to number of easy to implement and test methods:
// Random generator for insulting
private Random rgen = new Random();
// 1st index - category (name/verb/insult), 2nd index item within category
private static string[,] data;
private static string[] categories = new string[] {
"name", "verb", "insult",
};
// Input single categore, e.g. Names or Verbs
private static void InputCategory(int category) {
for (int i = 0; i < data.GetLength(1); ++i) {
Console.Write($"Please enter {categories[category]} #{i + 1}: ");
data[category, i] = Console.ReadLine();
}
}
// Input all categories
private static void InputData() {
Console.Write($"Enter the number of names, verbs, and objects: ");
// simplest; more accurate implementation uses int.TryParse()
int n = int.Parse(Console.ReadLine());
data = new string[categories.Length, n];
foreach(var int i = 0; i < categories.Length; ++i)
InputCategory();
}
To write an insult generator you should combine random items from each category
private static string[] Insults(int count) {
string[] result = new string[count];
// take count times a item from each category
for (int i = 0; i < count; ++i) {
StringBuilder sb = new StringBuilder
for (int c = 0; c < categories.Length; ++c) {
if (c > 0)
sb.Append(' ');
sb.Append(data[c, rgen.Next(data.GetLength(1))]);
}
result[i] = sb.ToString();
}
return ressult;
}
Having these methods you can put easily
private static void Main() {
int numberOfInsults = ....
InputData();
foreach (var insult in Insults(numberOfInsults))
Console.Write(insult);
...
}

Outputting a string array

I have 3 methods to 1. Take in strings as an array [zipCodes], 2. Output a menu for the user and 3. display the string array back to the user. The first 2 options are working and after testing I can say that the array is working and taking in strings, however I am having bother displaying them back to the user.
I have used this method with ints, it makes me think that the [i] is only for 1 character, an explanation would be greatly appreciated.
// Here is the code so far
static void Main(string[] args)
{
string[] zipCodes = new string[10];
string zCounter;
for (int i = 0; i < zipCodes.Length; i++)
{
Console.WriteLine("Please enter 10 destinations:");
zCounter = Convert.ToString(Console.ReadLine());
zCounter = zipCodes[i];
}
int sentinalNo;
Console.Clear();
Console.WriteLine("Please enter from the following options: ");
Console.WriteLine("1. Display order zipcodes.");
Console.WriteLine("2. Search zipcode.");
Console.WriteLine("3. Exit.");
sentinalNo = Convert.ToInt32(Console.ReadLine());
while (sentinalNo != 3)
{
switch (sentinalNo)
{
case 1:
DisplayZips(zipCodes);
break;
}
}
}
private static void DisplayZips(string[] zipCodes)
{
for (int i = 0; i < zipCodes.Length; i++)
{
// Why doesnt this work?
Console.WriteLine(zipCodes[i]);
}

You should assign input into the array items:
// array of 10 strings each of them is null
string[] zipCodes = new string[10];
...
for (int i = 0; i < zipCodes.Length; i++)
{
Console.WriteLine("Please enter 10 destinations:");
// Convert.ToString is redundant here
zCounter = Convert.ToString(Console.ReadLine());
// swapped: user input is assigned to array items
zipCodes[i] = zCounter;
}

reading two integers in one line using C#

i know how to make a console read two integers but each integer by it self like this
int a = int.Parse(Console.ReadLine());
int b = int.Parse(Console.ReadLine());
if i entered two numbers, i.e (1 2), the value (1 2), cant be parse to integers
what i want is if i entered 1 2 then it will take it as two integers

One option would be to accept a single line of input as a string and then process it.
For example:
//Read line, and split it by whitespace into an array of strings
string[] tokens = Console.ReadLine().Split();
//Parse element 0
int a = int.Parse(tokens[0]);
//Parse element 1
int b = int.Parse(tokens[1]);
One issue with this approach is that it will fail (by throwing an IndexOutOfRangeException/ FormatException) if the user does not enter the text in the expected format. If this is possible, you will have to validate the input.
For example, with regular expressions:
string line = Console.ReadLine();
// If the line consists of a sequence of digits, followed by whitespaces,
// followed by another sequence of digits (doesn't handle overflows)
if(new Regex(#"^\d+\s+\d+$").IsMatch(line))
{
... // Valid: process input
}
else
{
... // Invalid input
}
Alternatively:
Verify that the input splits into exactly 2 strings.
Use int.TryParse to attempt to parse the strings into numbers.

You need something like (no error-checking code)
var ints = Console
.ReadLine()
.Split()
.Select(int.Parse);
This reads a line, splits on whitespace and parses the split strings as integers. Of course in reality you would want to check if the entered strings are in fact valid integers (int.TryParse).

Then you should first store it in a string and then split it using the space as token.

Read the line into a string, split the string, and then parse the elements. A simple version (which needs to have error checking added to it) would be:
string s = Console.ReadLine();
string[] values = s.Split(' ');
int a = int.Parse(values[0]);
int b = int.Parse(values[1]);

string[] values = Console.ReadLine().Split(' ');
int x = int.Parse(values[0]);
int y = int.Parse(values[1]);

in 1 line, thanks to LinQ and regular expression (no type-checking neeeded)
var numbers = from Match number in new Regex(#"\d+").Matches(Console.ReadLine())
select int.Parse(number.Value);

string x;
int m;
int n;
Console.WriteLine("Enter two no's seperated by space: ");
x = Console.ReadLine();
m = Convert.ToInt32(x.Split(' ')[0]);
n = Convert.ToInt32(x.Split(' ')[1]);
Console.WriteLine("" + m + " " + n);
This Should work as per your need!

public static class ConsoleInput
{
public static IEnumerable<int> ReadInts()
{
return SplitInput(Console.ReadLine()).Select(int.Parse);
}
private static IEnumerable<string> SplitInput(string input)
{
return Regex.Split(input, #"\s+")
.Where(x => !string.IsNullOrWhiteSpace(x));
}
}

int a, b;
string line = Console.ReadLine();
string[] numbers= line.Split(' ');
a = int.Parse(numbers[0]);
b = int.Parse(numbers[1]);

Try this:
string numbers= Console.ReadLine();
string[] myNumbers = numbers.Split(' ');
int[] myInts = new int[myNumbers.Length];
for (int i = 0; i<myInts.Length; i++)
{
string myString=myNumbers[i].Trim();
myInts[i] = int.Parse(myString);
}
Hope it helps:)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace SortInSubSet
{
class Program
{
static int N, K;
static Dictionary<int, int> dicElements = new Dictionary<int, int>();
static void Main(string[] args)
{
while (!ReadNK())
{
Console.WriteLine("***************** PLEASE RETRY*********************");
}
var sortedDict = from entry in dicElements orderby entry.Key/3 , entry.Value ascending select entry.Value;
foreach (int ele in sortedDict)
{
Console.Write(ele.ToString() + " ");
}
Console.ReadKey();
}
static bool ReadNK()
{
dicElements = new Dictionary<int, int>();
Console.WriteLine("Please entere the No. of element 'N' ( Between 2 and 9999) and Subset Size 'K' Separated by space.");
string[] NK = Console.ReadLine().Split();
if (NK.Length != 2)
{
Console.WriteLine("Please enter N and K values correctly.");
return false;
}
if (int.TryParse(NK[0], out N))
{
if (N < 2 || N > 9999)
{
Console.WriteLine("Value of 'N' Should be Between 2 and 9999.");
return false;
}
}
else
{
Console.WriteLine("Invalid number: Value of 'N' Should be greater than 1 and lessthan 10000.");
return false;
}
if (int.TryParse(NK[1], out K))
{
Console.WriteLine("Enter all elements Separated by space.");
string[] kElements = Console.ReadLine().Split();
for (int i = 0; i < kElements.Length; i++)
{
int ele;
if (int.TryParse(kElements[i], out ele))
{
if (ele < -99999 || ele > 99999)
{
Console.WriteLine("Invalid Range( " + kElements[i] + "): Element value should be Between -99999 and 99999.");
return false;
}
dicElements.Add(i, ele);
}
else
{
Console.WriteLine("Invalid number( " + kElements[i] + "): Element value should be Between -99999 and 99999.");
return false;
}
}
}
else
{
Console.WriteLine(" Invalid number ,Value of 'K'.");
return false;
}
return true;
}
}
}

I have a much simpler solution, use a switch statement and write a message for the user in each case, using the Console.write() starting with a ("\n").
Here's an example of filling out an array with a for loop while taking user input. * Note: that you don't need to write a for loop for this to work*
Try this example with an integer array called arrayOfNumbers[] and a temp integer variable. Run this code in a separate console application and Watch how you can take user input on the same line!
int temp=0;
int[] arrayOfNumbers = new int[5];
for (int i = 0; i < arrayOfNumbers.Length; i++)
{
switch (i + 1)
{
case 1:
Console.Write("\nEnter First number: ");
//notice the "\n" at the start of the string
break;
case 2:
Console.Write("\nEnter Second number: ");
break;
case 3:
Console.Write("\nEnter Third number: ");
break;
case 4:
Console.Write("\nEnter Fourth number: ");
break;
case 5:
Console.Write("\nEnter Fifth number: ");
break;
} // end of switch
temp = Int32.Parse(Console.ReadLine()); // convert
arrayOfNumbers[i] = temp; // filling the array
}// end of for loop
The magic trick here is that you're fooling the console application, the secret is that you're taking user input on the same line you're writing your prompt message on. (message=>"Enter First Number: ")
This makes user input look like is being inserted on the same line. I admit it's a bit primitive but it does what you need without having to waste your time with complicated code for a such a simple task.