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How do I make my own String.Split() and Array.Reverse() built-in functions in one user-defined function to reverse a given string?

I have tried this:
using System;
using System.Collections;
using System.Collections.Generic;
public class HelloWorld
{
public static string reverseWords(string str){
ArrayList strArr = new ArrayList();
int start = 0;
string revStr = "";
for(int i = 0; i < str.Length; i++){
if(str[i] == ' '){ // if there's a space,
while(start <= str[i - 1]){ // loop thru the iterated values before space
strArr.Add(str[start]); // add them to the ArrayList
start++; // increment `start` until all iterated values are-
} // stored and also for the next word to loop thru
}
}
for(int j = strArr.Count - 1; j >= 0; j--){
revStr += strArr[j] + " "; // keep appending ArrayList values to the-
} // string from the last to the first value
return revStr;
}
public static void Main(string[] args)
{
Console.WriteLine(reverseWords("Our favorite color is Pink"));
//Expected output : Pink is color favorite Our
}
}
And it's giving this error:
System.IndexOutOfRangeException: Index was outside the bounds of the array.
Please help me understand why this is not working. And also, if there's better way to do this ReverseWord function manually(not using any built-in functions at all).
I'm sorry if this is such a noob question. Any constructive criticism is appreciated. Thanks!

Here is a little improved version of your code that actually works for what you are willing to do.
using System;
using System.Collections;
public class HelloWorld
{
public static string reverseWords(string str){
ArrayList strArr = new ArrayList();
string currentWordString = string.Empty;
string revStr = string.Empty;
for(int i = 0; i < str.Length; i++){
if(str[i] == ' '){ // if there's a space,
strArr.Add(currentWordString); // add the accumulated word to the array
currentWordString = string.Empty; // reset accumulator to be used in next iteration
}else {
currentWordString += str[i]; // accumulate the word
}
}
strArr.Add(currentWordString); // add last word to the array
for(int j = strArr.Count - 1; j >= 0; j--){
revStr += strArr[j] + " "; // keep appending ArrayList values to the-
} // string from the last to the first value
return revStr;
}
public static void Main(string[] args)
{
Console.WriteLine(reverseWords("Our favorite color is Pink"));
//Expected output : Pink is color favorite Our
}
}
I'll let you do the remaining. Like removing the trainling space at the end of the sentence. add seperators other than space (e.g comma, semicolons...)

Try this
"Our favorite color is Pink".Split('\u0020').Reverse().ToList().ForEach(x =>
{
Console.WriteLine(x);
});

This will help
public static string ReverseCharacters(string str)
{
if(str == null)
{
throw new ArgumentNullException(nameof(str));
}
int lastIndex = str.Length - 1;
char[] chars = new char[str.Length];
char temp;
for(int i = 0; i < str.Length/2+1; i++)
{
// Swap. You could refactor this to its own method if needed
temp = str[i];
chars[i] = str[lastIndex - i];
chars[lastIndex - i] = temp;
}
return new string(chars);
}
public static string ReverseWords(string str)
{
if (str == null)
{
throw new ArgumentNullException(nameof(str));
}
if (string.IsNullOrWhiteSpace(str))
{
return str;
}
string space = " ";
StringBuilder reversed = new StringBuilder();
// reverse every characters
var reversedCharacters = ReverseCharacters(str);
// split words (space being word separator here)
var reversedWords = reversedCharacters.Split(space);
// for every revered word characters, reverse it back one more time and append.
foreach(var reversedWord in reversedWords)
{
reversed.Append(ReverseCharacters(reversedWord)).Append(space);
}
// remove last extra space
reversed = reversed.Remove(reversed.Length - 1, 1);
return reversed.ToString();
}
Here is the test result:

Mutating to a new string array

I'm doing an exercise that says I have to enter a phrase and put it in array, then I have to delete all the repeated characters and show the new phrase.
I did it like this but I don't know how to get char from string array and put it into another string array.
PS: I must only use the basics of C# and arrays :(
namespace Exercice3
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Entrez une phrase SVP!!");
string phrase = Console.ReadLine();
string[] phraseArray = new string[]{ phrase };
string[] newPhrase = new string[phrase.Length];
for (int i = 0; i <= phrase.Length - 1; i++)
{
for (int j = 1; j <= phrase.Length - 1; j++)
{
if (phraseArray[i] != phraseArray[j])
newPhrase = phraseArray[i]; //Probleme here
}
}
Console.WriteLine(newPhrase);
}
}
}

something like this would do it. You don't have to do it this way...
using System;
using System.Collections.Generic;
public class Program
{
public static void Main()
{
var newColl = new List<char>();
foreach(char c in "aaabbbccc".ToCharArray())
{
if (!newColl.Contains(c))
newColl.Add(c);
}
Console.WriteLine(new string(newColl.ToArray()));
}
}
Output:
abc
Array-only method
using System;
using System.Collections.Generic;
public class Program
{
public static void Main()
{
const string orig = "aaabbbcccddd";
int origLen = orig.Length;
char[] newArr = new char[origLen]; // get max possible spots in arr
int newCount = 0;
for(int i = 0; i < origLen; i++)
{
bool yes = false;
for(int j = 0; j < newCount + 1; j++)
{
if (newArr[j] == orig[i])
{
yes = true;
break;
}
}
if (!yes)
{
newArr[newCount] = orig[i];
newCount++;
}
}
Console.WriteLine(new string(newArr));
}
}
Output:
abcd

The main problem here is that you are using arrays of strings. That is inappropriate because you are trying to iterate the characters of the string.
You need to construct your array of characters like this:
char[] phraseArray = phrase.ToCharArray();
This should allow you the ability to iterate the set of characters, check for duplicates, and form the new character array.

The reason why you're getting an IndexOutOfRangeException is because if you look at the two arrays:
string[] phraseArray = new string[]{ phrase };
And
string[] newPhrase = new string[phrase.Length];
The length of both arrays are completely different, phraseArray has a length of 1 and newPhrase will be set to the length of your phrase, so if you insert a world of more than 1 character both arrays will not match and then either:
if (phraseArray[i] != phraseArray[j])
Or
newPhrase = phraseArray[i];
Will fail, specially newPhrase = phraseArray[i];, because here you're trying to replace newPhrase an array, for a character phrase[i]. Basically your solution won't work. So what you can do is do what #Travis suggested, basically change your arrays from String[]to char[], then:
char[] phraseArray = phrase.ToCharArray();
Or Instead of using arrays you can just use another string to filter your phrase. The first string being your phrase and the second would be the string you'd add your non repeated characters to. basically this:
Console.WriteLine("Entrez une phrase SVP!!");
string phrase = Console.ReadLine();
string newPhrase = "";
// loop through each character in phrase
for (int i = 0; i < phrase.Length; i++) {
// We check if the character of phrease is within our newPhrase, if it isn't we add it, otherwise do nothing
if (newPhrase.IndexOf(phrase[i]) == -1)
newPhrase += phrase[i]; // here we add it to newPhrase
}
Console.WriteLine(newPhrase);
Don't forget to read the comments in the code.
Edit:
Based on the comments and suggestions given I implemented a similar solution:
Console.WriteLine("Entrez une phrase SVP!!");
char[] phrase = Console.ReadLine().ToCharArray();
char[] newPhrase = new char[phrase.Length];
int index = 0;
// loop through each character in phrase
for (int i = 0; i < phrase.Length; i++) {
// We check if the character of phrease is within our newPhrase, if it isn't we add it, otherwise do nothing
if (Array.IndexOf(newPhrase, phrase[i]) == -1)
newPhrase[index++] = phrase[i]; // here we add it to newPhrase
}
Console.WriteLine(newPhrase);

Noob needing help on breaking out of loop

I'm very sorry this is such an easy question, I'm just starting out. I've created code that allows a user to enter a number of random dice rolls, and outputs the sum of those rolls. I've now been asked to create a loop that repeats these steps, including the prompt, until the user types 'quit'. My issue is that my code converts the string to an integer, so typing anything kills the code. Any tips of how to insert the loop and break? My code is:
static void Main(string[] args)
{
Random random = new Random();
Console.WriteLine("Enter a number of dice to roll:");
string numberDiceString = Console.ReadLine();
int numberDice = Convert.ToInt32(numberDiceString);
int total = 0;
for (int index = 0; index < numberDice; index++)
{
int DieRoll = random.Next(6) + 1;
total += DieRoll;
}
Console.WriteLine(total);
Console.ReadKey();
}

I wouldn't use a "while(true)" statement. As someone pointed out in the comments i would prefer using the right condition in there.
That being said i would do it this way:
static void Main(string[] args)
{
Random random = new Random();
string numberDiceString;
int numberDice;
Console.WriteLine("Enter a number of dice to roll:");
while ((numberDiceString = Console.ReadLine()) != "quit")
{
bool parsed = int.TryParse(numberDiceString, out numberDice);
if (!parsed)
{
//Handle the error. The user input was not a number or "quit" word
break;
}
int total = 0;
for (int index = 0; index < numberDice; index++)
{
int DieRoll = random.Next(6) + 1;
total += DieRoll;
}
Console.WriteLine(total);
Console.WriteLine("Enter a number of dice to roll:");
}
}
I have to say that i prefer this way because you can easily see when the loop will stop. Also i added an error handling that you should be doing (What happen if the user enters any words that are not numbers?).
Hope this helps.

This change should be fairly simple. What you need to do is to create a while loop, and then a check before you actually parse for an int. The psuedocode for this would be something like.
while(true) {
//Ask for input
//Check if it equals "quit"
//If so -> break;
//If not convert to int
//For Loop for dice rolls
//Print Total
}
I'm sure it could be a little more elegant than this, and you would want to put some more checks to make sure that invalid input doesn't crash the program, but it should get the job done.

This is a very simple solution that shows how to parse the user input.
using System;
namespace Simpleton
{
class Program
{
static public int GetChoice()
{
int choice = 0;
while (true)
{
Console.Write("Enter number of rolls or \"quit\" to finish: ");
var answer = Console.ReadLine();
if (String.Compare(answer, "quit", true) == 0)
{
return 0; // Done
}
if (Int32.TryParse(answer, out choice))
{
return choice;
}
}
}
static void Main(string[] args)
{
var choice = 0;
while ((choice = GetChoice()) > 0)
{
Console.WriteLine($"You'll be looping {choice} times.");
for (int tries = 0; tries < choice; tries++)
{
// Looping
}
}
}
}
}

Try this code:
static void Main(string[] args)
{
Random random = new Random();
while(true)
{
String numberDiceString = "";
int numberDice = 0;
Console.WriteLine("Enter a number of dice to roll:");
numberDiceString = Console.ReadLine();
if (numberDiceString == "quit") { return; }
int total = 0;
if (Int32.TryParse(numberDiceString, out numberDice))
{
total = 0;
for (int index = 0; index < numberDice; index++)
{
int DieRoll = random.Next(6) + 1;
total += DieRoll;
}
}
Console.WriteLine(total);
}
}

I'm not a C# programmer, but you can test for "quit" explicitly and use a goto
BeginLoop:
Console.WriteLine("Enter a number of dice to roll:");
string numberDiceString = Console.ReadLine();
if (numberDiceString == "quit")
{
goto EndLoop;
}
int numberDice = Convert.ToInt32(numberDiceString);
/* Rest of code you want to do per iteration */
goto BeginLoop;
EndLoop:

Reverse word of full sentence using for loop in c#

I want to print the string in reverse format in for loop:
Input: I'm Learning c#
Output: c# Learning I'm
No Split functions and reverse functions should be used, it has to do only with forloop.
for (int i = m.Length - 1; i >= 0; i--)
{
b[j]=a[i];
j++;
if(a[i]==' '|| a[i]==0)
{
for (int x = b.Length - 1; x >= 0; x--)
{
c[k] = b[x];
Console.Write(c[k]);
k++;
}
}
} Console.ReadKey();

You have to create an array of the words in the sentence:
var words = input.Split(' ');
Then you just loop through the above array from the end to the start:
for(int i=words.Length-1; i>=0; i--)
{
Console.Write(words[i]+" ");
}

With LINQ and string methods you can simplify it:
var reversedWords = input.Split().Reverse(); // Split without parameters will use space, tab and new-line characters as delimiter
string output = string.Join(" ", reversedWords); // build reversed words, space is delimiter

Use Stack<Queue<char>>
Hey if you want to show off your knowledge of data structures, use a queue and a stack! This makes for a very concise answer as well.
You want the sentence to be LIFO with respect to words but FIFO with respect to letters within words, so you need a stack (which are LIFO) of queues (which are FIFO). You can take advantage of the fact that a string, a queue<char>, and a stack<char> all expose IEnumerable<char> as well, so it's easy to convert back and forth; once you have all the characters ordered in your data structure, you can extract the whole thing as a character array using SelectMany(), which you can pass to a string constructor for the final answer.
This solution uses no Split() or Reverse() functions, as required.
public static string ReverseSentence(string input)
{
var word = new Queue<char>();
var sentence = new Stack<IEnumerable<char>>( new [] { word } );
foreach ( char c in input )
{
if (c == ' ')
{
sentence.Push( " " );
sentence.Push( word = new Queue<char>() );
}
else
{
word.Enqueue(c);
}
}
return new string( sentence.SelectMany( w => w ).ToArray() );
}
Usage:
public void Test()
{
var input = "I'm Learning c#";
var output = ReverseSentence(input);
Console.WriteLine(output);
}
Output:
c# Learning I'm
DotNetFiddle

Without split and reverse, I modify your logic little bit to achieve what you need
namespace MyNamespace
{
public class Program
{
public static void Main(string[] args)
{
var m="this is mystring";
var b = new char [m.Length];
var j=0;
//Your code goes here
for (int i = m.Length - 1; i >= 0; i--)
{
b[j]=m[i];
j++;
if(m[i]==' ' || i==0)
{
if(i==0)
{
b[j]=' ';
}
for (int x = b.Length - 1; x >= 0; x--)
{
Console.Write(b[x]);
}
b=new char[m.Length];
j=0;
}
}
Console.ReadKey();
Console.WriteLine("Hello, world!");
}
}
}
Input: "this is mystring"
Output: "mystring is this"

Here is a simple console application for your question
Without using Reverse and Split methods (just for loop)
class Program
{
static void Main()
{
string input = "I'm learning C#";
string[] result = new string[3];
int arrayIndex = 0;
string tempStr = "";
// Split string
for (int i = 0; i < input.Length; i++)
{
tempStr += input[i].ToString();
if (input[i] != ' ')
{
result[arrayIndex] = tempStr;
}
else
{
tempStr = "";
arrayIndex++;
}
}
// Display Result
for (int i = result.Length - 1; i >= 0; i--)
{
System.Console.Write(result[i] + ' ');
}
System.Console.WriteLine();
}
}
Press Ctrl + F5 to run the program
Output: C# learning I'm

How can I fill an array with user input in case of numbers

I would like my program to fill an array with user input, but with an numeric input (then program will make specific calculations with that numbers, but it's not important for now).
If no input is done, program should stop reading numbers and print it. I have a couple of errors, especially in case of parsing, because I have tried a couple of solutions, and I have no idea in which part of code and maybe what way, numbers in an array should be parsed to avoid receiving an "cannot implicitly convert type string to int" or "cannot implicitly convert type int[] to int".
This how my code looks like:
public static void Main (string[] args)
{
int[] userInput = new int[100];
int xuserInput = int.Parse (userInput);
for (int i = 0; i<userInput.Length; i++)
{
userInput[i] = Console.ReadLine ();
if (userInput == "")
break;
}
Console.WriteLine (userInput);
}

you should take the input to a string and try to parse it to integer:
public static void Main(string[] args)
{
int[] userInput = new int[100];
int counter = 0;
for (counter = 0; counter < userInput.Length; counter++)
{
string input = Console.ReadLine();
if (input == "")
break;
else
int.TryParse(input, out userInput[counter]);
}
for (int i = 0; i < counter; i++)
{
Console.WriteLine(userInput[i]);
}
Console.ReadLine();
}
try parse will not throw exception like parse will.
if you decide to use parse, catch exceptions

Try this:
int[] userInputs = new int[100];
int parsedInput;
int inputs = 0;
bool stop = false;
while (inputs < 100 && !stop)
{
string userInput = Console.ReadLine();
if (userInput == "")
{
stop = true;
}
else if (Int32.TryParse(userInput, out parsedInput))
{
userInputs[i] = parsedInput;
inputs++;
}
else
{
Console.WriteLine("Please enter a number only!");
}
}
for each (int number in userInputs)
{
Console.WrietLine(number.ToString());
}
This code does a few things.
First, a while loop is used to ensure the user inputs 100 numbers or doesn't enter any data.
Next, it gets the input from the user. If it's an empty input, it sets the stop flag to true, which will exit the loop.
If the input wasn't empty, it uses TryParse to determine if the input is a number. If it is, it returns true and the converted input is added to the array and the counter incremented.
If the parse fails, the user is prompted to enter a number.
Once the array is filled, it loops through the array and prints out each input.

The problem is that you are parsing userInput which is an array with int.Parse instead of parsing the input you got by Console.ReadLine()
int xuserInput = int.Parse (userInput); // Remove this statement.
For parsing user input you need to parse like this
string input = Console.ReadLine ();
if (input == "")
break;
else
int.TryParse(input, out userInput[i]);

try this.
public static void Main (string[] args)
{
int[] userInput = new int[100];
int xuserInput = int.Parse (userInput);
for (int i = 0; i<userInput.Length; i++)
{
int temp = int.Parse(Console.ReadLine());
userInput[i] = temp;
if (userInput == "")
break;
}
Console.WriteLine (userInput);
}

You just might want to use this
static void Main(string[] args)
{
int[] userInput = new int[100];
string recievedInput = "";
for (int i = 0; i<userInput.Length; i++)
{
recievedInput = Console.ReadLine();
int.TryParse(recievedInput, out userInput[i]);
if (recievedInput == "")
break;
}
Console.WriteLine (userInput); //this will only print the type name of Userinput not all element
}

The following program reads numbers from user.
If user enters an invalid number, then it reports with the message: Not a valid number.
If user enters nothing, then the program prints all the numbers entered by the user.
class Program
{
static void Main(string[] args)
{
int[] userInput = new int[10];
for(int count = 0; count <= 9; count++)
{
int number;
string input = Console.ReadLine();
bool result = Int32.TryParse(input, out number);
if (result)
{
userInput[count] = number;
}
else if (!result)
{
if (input != string.Empty)
Console.WriteLine("Not a valid number.");
else if (input.Equals(string.Empty))
{
foreach (var item in userInput)
{
Console.WriteLine(item.ToString());
}
Console.WriteLine("Press any key to continue...");
Console.ReadKey(true);
return;
}
}
}
}
}
Please let me know, if this is okay to you.