How to create Palindrome with Reverse method - c#

I am learning C# but I just stack at some simple task with creating Palindrome function. I decided to change string to char array and then use reverse method and compare initial char array to reversed one. But it is look like reverse method do not work when put into if statement, or maybe I made mistake somewhere else??
void IsPalindrome(string x)
{
bool isEqual = true;
char[] charArr = x.ToCharArray();
char[] reversed = charArr;
Array.Reverse(reversed);
for (int i = 0; i < reversed.Length; i++)
{
if (reversed[i] != charArr[i])
{
isEqual = false;
}
}
if (isEqual == true)
{
Console.WriteLine($"True, {x.Length}");
}
else
{
Console.WriteLine($"False, {x.Length}");
}
}
Console.WriteLine("Type a string:");
string? userString = Console.ReadLine();
IsPalindrome(userString);

charArr and reversed are pointing to the same address in memory. Try this instead:
void IsPalindrome(string x)
{
bool isEqual = true;
char[] reversed = x.ToCharArray();
Array.Reverse(reversed);
for (int i = 0; i < reversed.Length; i++)
{
if (reversed[i] != x[i])
{
isEqual = false;
}
}
if (isEqual == true)
{
Console.WriteLine($"True, {x.Length}");
}
else
{
Console.WriteLine($"False, {x.Length}");
}
}
Console.WriteLine("Type a string:");
string? userString = Console.ReadLine();
IsPalindrome(userString);

Related

How can I use List.Contains

I have assignment to make Hangman game with methods, so far everything is going ok until I realized that the word that I input by char when has two consecutive characters it can't get the following if statement
if (correctGuesses.Count == randomWord.Length)
{
Console.WriteLine("You won the word is: {0}", randomWord);
break;
}
and thus I can never finish the game if the word is something like Green
I was trying to use List.Contains('*') if contains it to continue if not to break and to write the Word thus to win, but it fails if I put '!' in front or if I don't put it, it becomes a endless loop . Could you please help me if there is a way to use Contains in a way that will not search only for one symbol but will check for every single one until there is no more.
I will post the code here.
static string GeneratingRandomWords()
{
Random r = new Random();
List<string> words = new List<string>() { /*"Cat", "Dog", "Eagle", "Lion", "Shark",*/ "Green" };
string word = words[r.Next(0, words.Count)];
return word;
}
static char Input()
{
char inputt = char.Parse(Console.ReadLine());
return inputt;
}
static char[] TransformingCharToInvisible(string randomWord)
{
char[] charFromString = randomWord.ToCharArray();
for (int i = 0; i < randomWord.Length; i++)
{
charFromString[i] = '*';
}
Console.WriteLine(charFromString);
return charFromString;
}
static int CorrectGuesses(char input, string randomWord, int correct)
{
if (randomWord.Contains(input))
{
Console.WriteLine("Next");
correct++;
}
return correct;
}
static int Lives(string randomWord, char input, int lives)
{
if (!randomWord.Contains(input))
{
Console.WriteLine("Try another one");
lives--;
}
return lives;
}
static List<char> CorrectWord(List<char> correctGuesses, string randomWord, char input)
{
if (randomWord.Contains(input))
{
correctGuesses.Add(input);
char[] charFromString = randomWord.ToCharArray();
for (int i = 0; i < randomWord.Length; i++)
{
charFromString[i] = '*';
if (correctGuesses.Contains(randomWord[i]))
{
charFromString[i] = randomWord[i];
}
}
Console.WriteLine(charFromString);
}
return correctGuesses;
}
static void Main(string[] args)
{
string randomWord = GeneratingRandomWords();
TransformingCharToInvisible(randomWord);
List<char> correctGuesses = new List<char>();
int lives = 10;
int correct = 0;
//bool won = true;
while (true)
{
Console.WriteLine("Write a char");
char input = Input();
correct = CorrectGuesses(input, randomWord, correct);
lives = Lives(randomWord, input, lives);
if (correctGuesses.Contains(input))
{
Console.WriteLine("You've already tried '{0}', and it was correct!", input);
continue;
}
correctGuesses = CorrectWord(correctGuesses, randomWord, input);
if (lives == 0)
{
Console.WriteLine("You lose sorry, try againg next time ");
break;
}
if (correctGuesses.Count == randomWord.Length)
{
Console.WriteLine("You won the word is: {0}", randomWord);
break;
}
}
}
Here a simplified version of your code where i did not add all the error checking but the basics use the required Contains to check if letters are found
static void Main(string[] args)
{
var lives = 10;
var correctGuesses = new List<char>();
var word = "green";
while (true)
{
Console.WriteLine("Guess a letter? ");
// deliberatly just check for 1 character for simplicity reasons
var input = Console.ReadLine()[0];
// if already guessed give a chance to the user to retry
if (correctGuesses.Contains(input))
{
Console.WriteLine("Letter already guessed");
}
else
{
// if the word contains the letter
if (word.Contains(input))
{
// add as a correct guess
correctGuesses.Add(input);
Console.WriteLine("Letter found");
}
else
{
// letter dont exist remove a life
lives--;
Console.WriteLine("Letter not found");
}
}
// check if the user still have lives
if (lives == 0)
{
Console.WriteLine("You lost");
break;
}
// check if the amount of distinct character in the word match
// the amount found. This mean the word is completly guessed
else if (word.Distinct().Count() == correctGuesses.Count())
{
Console.WriteLine("You won you found the word");
break;
}
}
Console.ReadKey();
}
I didn't understand you very well
but I modified your code like this :
private static bool IsCorrectGuess(char input, string actualWord)
{
return actualWord.Contains(input);
}
private static void WriteCorrectGuesses(ICollection<char> correctGuesses, string randomWord)
{
char[] charFromString = randomWord.ToCharArray();
for (var i = 0; i < randomWord.Length; i++)
{
charFromString[i] = '*';
if (correctGuesses.Contains(randomWord[i]))
charFromString[i] = randomWord[i];
}
Console.WriteLine(charFromString);
}
private static string GeneratingRandomWords()
{
var r = new Random();
var words = new List<string>
{
/*"Cat", "Dog", "Eagle", "Lion", "Shark",*/ "Green"
};
return words[r.Next(0, words.Count)];
}
private static char Input()
{
return char.Parse(Console.ReadLine() ?? throw new InvalidOperationException());
}
private static void Main(string[] args)
{
string randomWord = GeneratingRandomWords();
var correctGuesses = new List<char>();
WriteCorrectGuesses(correctGuesses, randomWord);
var lives = 10;
var correct = 0;
//bool won = true;
while (true)
{
Console.WriteLine("Write a char");
char input = Input();
if (IsCorrectGuess(input, randomWord))
{
// correct letter
int score = randomWord.ToCharArray().Count(item => item == input);
for (var i = 0; i < score; i++)
{
correctGuesses.Add(input);
correct++;
}
WriteCorrectGuesses(correctGuesses, randomWord);
if (correctGuesses.Count == randomWord.Length)
{
Console.WriteLine("You won the word is: {0}", randomWord);
Console.Read();
break;
}
Console.WriteLine("Next");
}
else
{
// wrong letter
Console.WriteLine($"Try another one. You still have {lives} to try.");
lives--;
}
if (lives == 0)
{
Console.WriteLine("You lose sorry, try again next time ");
break;
}
}
}

Foreach won't return elements of char list

So im making this hangman game, as Im trying to learn C# but now im stuck with System.Collection.Generic.List'1[System.Char]. What im trying to do is to save wrong answers into List nepravilne, look into functions izpis and igra
class Program
{
static private int _sccore;
static void Main(string[] args)
{
string beseda;
int dolzina;
bool play=true;
char input;
do
{
beseda = izberi_besedo();
dolzina = beseda.Length;
igra(beseda, dolzina);
Console.WriteLine("Vnesite Y za nadaljevanje ali N za zakljucitev igre.");
input = char.Parse(Console.ReadLine());
if (input.Equals('y'))
{
play = true;
Console.WriteLine("play {0}",play);
}
if (input.Equals('n'))
{
play = false;
Console.WriteLine("play {0}", play);
}
} while (play == true);
}
static private string izberi_besedo() {
string[] besede = { "voda", "ladija", "letalo", "motor", "klavir", "harmonika", "saksofon", "oklep", "penkalo", "tiskalnik", "miza", "copat", "krogla", "klobuk", "gumb", "harfa", "kontrabas", "mandarina", "les", "knjiga", "vlak", "vijak", "struna", "kozarec" };
Random rnd = new Random();
int stevilka = rnd.Next(0, 23);
string beseda = besede[stevilka];
return beseda;
}
static private void igra (string beseda, int dolzina){
int i, poizkusi = 0;
int pravilne = 0;
bool endloop = false;
char crka;
List<char> nepravilne = new List<char>();//declaring char list for wrong words
string[] odkrite = new string[dolzina];
for(i=0; i<dolzina; i++) { odkrite[i] = "_"; }
do {
izpis(odkrite,nepravilne); //izpis - function which returns just text, we are inputing list nepravilne, which are wrong answers
vpis(out crka);
if (!(beseda.Contains(crka)))//if word doesen't contain letter
{
poizkusi++;
_sccore--;
nepravilne.Add(crka);//add that letter to list
}
for (i = 0; i<dolzina; i++)
{
if (crka.Equals(beseda[i]))
{
odkrite[i] = Convert.ToString(crka);
pravilne++;
_sccore++;
}
}
Console.Clear();
if (pravilne >= dolzina || poizkusi >= 4)endloop = true;
} while (endloop==false);
}
static private void vpis(out char crka)
{
string vpis;
bool stevilka=false, status;
Console.WriteLine("\nVnesite crko za ugibanje besede");
vpis = Console.ReadLine();
stevilka = IsNumeric(vpis);
if (vpis.Length == 1 && stevilka==false)
{
crka = Convert.ToChar(vpis);
}
else
{
do
{
status = false;
if (vpis.Length!=1) Console.WriteLine("Vnesli ste prevec crk, poizkusite ponovno");
if(stevilka==true) Console.WriteLine("Vnesli ste stevilko, poizkusite ponovno");
vpis = Console.ReadLine();
stevilka = IsNumeric(vpis);
if (vpis.Length == 1 && stevilka == false)
{
status = true;
}
} while (status==false);
crka = Convert.ToChar(vpis);
}
}
private static bool IsNumeric(string vpis)
{
int number;
return int.TryParse(vpis, out number);
}
private static void izpis(string[] odkrite, List<char> nepravilne)
{
Console.Write("Rezultat {0} | ", _sccore);
foreach (char element in nepravilne)//write out char elements which contain letter
{
Console.Write("{0} ", nepravilne);
}
Console.WriteLine();
foreach (string element in odkrite)
{
Console.Write("{0} ", element);
}
}
}
}
I think you have a typo in the following code, i.e I think you are intending to print the variable element in the loop and not nepravilne:
foreach (char element in nepravilne)
{
Console.Write("{0} ", nepravilne);
}
Should be as follows instead?
foreach (char element in nepravilne)
{
Console.Write("{0} ", element);
}

Check string on duplicate char

first time I write on the SO, because he could not find solution myself.
At the interview, I was given the task to write a method that checks the characters in the string to a unique.
Requirements: not using LINQ. Desirable: do not use additional data types (Dictionary, HashSet...etc. Arrays and lists Allowed)
Example:
"Hello" - return false; "Helo" - return true
My implementation:
static HashSet<char> charSet = new HashSet<char>();
static bool IsUniqueChar(string str)
{
foreach (char c in str)
{
charSet.Add(c);
}
return charSet.Count() == str.Length;
}
But it does not meet the requirements of data types, and is not the best performance...
I also tried the approach with a dictionary:
static Dictionary<char,bool> charSetDictionary = new Dictionary<char,bool>();
static bool IsUniqueChar(string str)
{
try
{
foreach (char c in str)
{
charSetDictionary.Add(c,true);
}
}
catch
{
return false;
}
But he is no better than the previous.
I will welcome any idea how to solve this task better?
p.s
static void Main(string[] args)
{
Stopwatch sw = Stopwatch.StartNew();
IsUniqueChar("Hello");
sw.Stop();
Console.WriteLine("Elapsed={0}", sw.Elapsed); //~005044
}
The fastest way uses HashSet<char>:
var set = new HashSet<char>();
foreach(var c in input)
{
if(!set.Add(c))
return false;
}
return true;
It's O(n) solution in worst case (input is unique). Returns false as soon as first duplicate is found.
Without HashSet<char> you can easily transform string to char[], sort it and check if you have two consecutive items with the same value.
var chars = input.ToCharArray();
chars.Sort();
for(int i = 1; i < chars.Length; i++)
{
if(chars[i-1] == chars[i])
return false;
}
return true;
Sort is O(n log(n)) and so is the entire function.
All answers so far are based on the assumption that one .NET char corresponds to one Unicode character. This is only true for characters in the Basic Multilingual Plane. Characters outside the BMP are encoded using two char objects (surrogate pair).
The following code handles this special case:
HashSet<string> set = new HashSet<string>();
for (int i = 0; i < str.Length; i++)
{
string s;
if (char.IsHighSurrogate(str[i]))
{
s = str.Substring(i, 2);
i++;
}
else
{
s = str.Substring(i, 1);
}
if (!set.Add(s))
{
return false;
}
}
return true;
Suppose the test string is passed through textBox1, then it follows:
string tst;
int i,j, stat =0;
tst = textBox1.Text;
for (i = 0; i < tst.Length; i++)
{
for (j = 0; j < tst.Length; j++)
{
if ((tst[i] == tst[j]) && (i != j))
{
stat = 1;
break;
}
else continue;
}
if (stat == 1) break;
else continue;
}
if (stat == 1) MessageBox.Show("False");
else MessageBox.Show("True");
Every string is an array of characters.
Most likely, your interviewer would like to see an approach using knowledge about Unicode:
static bool[] charsHash = new bool[512];
static bool IsUniqueChar(string str)
{
if (str.Length > 512) return false;
foreach (char c in str)
{
bool alreadyExist = charsHash[(int)c];
if (alreadyExist) return false;
else charsHash[(int)c] = !alreadyExist;
}
return true;
}
static void Main(string[] args)
{
Stopwatch sw = Stopwatch.StartNew();
IsUniqueChar("Hello");
sw.Stop();
Console.WriteLine("Elapsed={0}", sw.Elapsed);//~000283
}

Check if a string is a palindrome

I have a string as input and have to break the string in two substrings. If the left substring equals the right substring then do some logic.
How can I do this?
Sample:
public bool getStatus(string myString)
{
}
Example: myString = "ankYkna", so if we break it into two substring it would be:
left-part = "ank",
right-part = "ank" (after reversal).
Just for fun:
return myString.SequenceEqual(myString.Reverse());
public static bool getStatus(string myString)
{
string first = myString.Substring(0, myString.Length / 2);
char[] arr = myString.ToCharArray();
Array.Reverse(arr);
string temp = new string(arr);
string second = temp.Substring(0, temp.Length / 2);
return first.Equals(second);
}
int length = myString.Length;
for (int i = 0; i < length / 2; i++)
{
if (myString[i] != myString[length - i - 1])
return false;
}
return true;
Using LINQ and off course far from the best solution
var original = "ankYkna";
var reversed = new string(original.Reverse().ToArray());
var palindrom = original == reversed;
A single line of code using Linq
public static bool IsPalindrome(string str)
{
return str.SequenceEqual(str.Reverse());
}
public static bool IsPalindrome(string value)
{
int i = 0;
int j = value.Length - 1;
while (true)
{
if (i > j)
{
return true;
}
char a = value[i];
char b = value[j];
if (char.ToLower(a) != char.ToLower(b))
{
return false;
}
i++;
j--;
}
}
//This c# method will check for even and odd lengh palindrome string
public static bool IsPalenDrome(string palendromeString)
{
bool isPalenDrome = false;
try
{
int halfLength = palendromeString.Length / 2;
string leftHalfString = palendromeString.Substring(0,halfLength);
char[] reversedArray = palendromeString.ToCharArray();
Array.Reverse(reversedArray);
string reversedString = new string(reversedArray);
string rightHalfStringReversed = reversedString.Substring(0, halfLength);
isPalenDrome = leftHalfString == rightHalfStringReversed ? true : false;
}
catch (Exception ex)
{
throw ex;
}
return isPalenDrome;
}
In C# :
public bool EhPalindromo(string text)
{
var reverseText = string.Join("", text.ToLower().Reverse());
return reverseText == text;
}
This is a short and efficient way of checking palindrome.
bool checkPalindrome(string inputString) {
int length = inputString.Length;
for(int i = 0; i < length/2; i++){
if(inputString[i] != inputString[length-1-i]){
return false;
}
}
return true;
}
This way is both concise in appearance & processes very quickly.
Func<string, bool> IsPalindrome = s => s.Reverse().Equals(s);
public static bool IsPalindrome(string word)
{
//first reverse the string
string reversedString = new string(word.Reverse().ToArray());
return string.Compare(word, reversedString) == 0 ? true : false;
}
Out of all the solutions, below can also be tried:
public static bool IsPalindrome(string s)
{
return s == new string(s.Reverse().ToArray());
}
String extension method, easy to use:
public static bool IsPalindrome(this string str)
{
str = new Regex("[^a-zA-Z]").Replace(str, "").ToLower();
return !str.Where((t, i) => t != str[str.Length - i - 1]).Any();
}
private void CheckIfPalindrome(string str)
{
//place string in array of chars
char[] array = str.ToCharArray();
int length = array.Length -1 ;
Boolean palindrome =true;
for (int i = 0; i <= length; i++)//go through the array
{
if (array[i] != array[length])//compare if the char in the same positions are the same eg "tattarrattat" will compare array[0]=t with array[11] =t if are not the same stop the for loop
{
MessageBox.Show("not");
palindrome = false;
break;
}
else //if they are the same make length smaller by one and do the same
{
length--;
}
}
if (palindrome) MessageBox.Show("Palindrome");
}
use this way from dotnetperls
using System;
class Program
{
/// <summary>
/// Determines whether the string is a palindrome.
/// </summary>
public static bool IsPalindrome(string value)
{
int min = 0;
int max = value.Length - 1;
while (true)
{
if (min > max)
{
return true;
}
char a = value[min];
char b = value[max];
// Scan forward for a while invalid.
while (!char.IsLetterOrDigit(a))
{
min++;
if (min > max)
{
return true;
}
a = value[min];
}
// Scan backward for b while invalid.
while (!char.IsLetterOrDigit(b))
{
max--;
if (min > max)
{
return true;
}
b = value[max];
}
if (char.ToLower(a) != char.ToLower(b))
{
return false;
}
min++;
max--;
}
}
static void Main()
{
string[] array =
{
"A man, a plan, a canal: Panama.",
"A Toyota. Race fast, safe car. A Toyota.",
"Cigar? Toss it in a can. It is so tragic.",
"Dammit, I'm mad!",
"Delia saw I was ailed.",
"Desserts, I stressed!",
"Draw, O coward!",
"Lepers repel.",
"Live not on evil.",
"Lonely Tylenol.",
"Murder for a jar of red rum.",
"Never odd or even.",
"No lemon, no melon.",
"Senile felines.",
"So many dynamos!",
"Step on no pets.",
"Was it a car or a cat I saw?",
"Dot Net Perls is not a palindrome.",
"Why are you reading this?",
"This article is not useful.",
"...",
"...Test"
};
foreach (string value in array)
{
Console.WriteLine("{0} = {1}", value, IsPalindrome(value));
}
}
}
If you just need to detect a palindrome, you can do it with a regex, as explained here. Probably not the most efficient approach, though...
That is non-trivial, there is no built in method to do that for you, you'll have to write your own. You will need to consider what rules you would like to check, like you implicitly stated you accepted reversing of one string. Also, you missed out the middle character, is this only if odd length?
So you will have something like:
if(myString.length % 2 = 0)
{
//even
string a = myString.substring(0, myString.length / 2);
string b = myString.substring(myString.length / 2 + 1, myString.lenght/2);
if(a == b)
return true;
//Rule 1: reverse
if(a == b.reverse()) //can't remember if this is a method, if not you'll have to write that too
return true;
etc, also doing whatever you want for odd strings
This C# method will check for even and odd length palindrome string (Recursive Approach):
public static bool IsPalindromeResursive(int rightIndex, int leftIndex, char[] inputString)
{
if (rightIndex == leftIndex || rightIndex < leftIndex)
return true;
if (inputString[rightIndex] == inputString[leftIndex])
return IsPalindromeResursive(--rightIndex, ++leftIndex, inputString);
else
return false;
}
public Boolean IsPalindrome(string value)
{
var one = value.ToList<char>();
var two = one.Reverse<char>().ToList();
return one.Equals(two);
}
class Program
{
static void Main(string[] args)
{
string s, revs = "";
Console.WriteLine(" Enter string");
s = Console.ReadLine();
for (int i = s.Length - 1; i >= 0; i--) //String Reverse
{
Console.WriteLine(i);
revs += s[i].ToString();
}
if (revs == s) // Checking whether string is palindrome or not
{
Console.WriteLine("String is Palindrome");
}
else
{
Console.WriteLine("String is not Palindrome");
}
Console.ReadKey();
}
}
public bool IsPalindroom(string input)
{
input = input.ToLower();
var loops = input.Length / 2;
var higherBoundIdx = input.Length - 1;
for (var lowerBoundIdx = 0; lowerBoundIdx < loops; lowerBoundIdx++, higherBoundIdx--)
{
if (input[lowerBoundIdx] != input[higherBoundIdx])
return false;
}
return true;
}
Here is an absolutely simple way to do this,
Receive the word as input into a method.
Assign a temp variable to the original value.
Loop through the initial word, and add the last character to the reversal that you are constructing until the inital word has no more characters.
Now use the spare you created to hold the original value to compare to the constructed copy.
This is a nice way as u don't have to cast ints and doubles. U can just pass them to the method in their string representation by using the ToString() method.
public static bool IsPalindrome(string word)
{
string spare = word;
string reversal = null;
while (word.Length > 0)
{
reversal = string.Concat(reversal, word.LastOrDefault());
word = word.Remove(word.Length - 1);
}
return spare.Equals(reversal);
}
So from your main method,
For even and odd length strings u just pass the whole string into the method.
Since a palindrome also includes numbers, words, sentences, and any combinations of these, and should ignore punctuation and case, (See Wikipedia Article)
I propose this solution:
public class Palindrome
{
static IList<int> Allowed = new List<int> {
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'h',
'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
'1', '2', '3', '4', '5', '6', '7', '8', '9',
'0'
};
private static int[] GetJustAllowed(string text)
{
List<int> characters = new List<int>();
foreach (var c in text)
characters.Add(c | 0x20);
return characters.Where(c => Allowed.Contains(c)).ToArray();
}
public static bool IsPalindrome(string text)
{
if(text == null || text.Length == 1)
return true;
int[] chars = GetJustAllowed(text);
var length = chars.Length;
while (length > 0)
if (chars[chars.Length - length] != chars[--length])
return false;
return true;
}
public static bool IsPalindrome(int number)
{
return IsPalindrome(number.ToString());
}
public static bool IsPalindrome(double number)
{
return IsPalindrome(number.ToString());
}
public static bool IsPalindrome(decimal number)
{
return IsPalindrome(number.ToString());
}
}
static void Main(string[] args)
{
string str, rev="";
Console.Write("Enter string");
str = Console.ReadLine();
for (int i = str.Length - 1; i >= 0; i--)
{
rev = rev + str[i];
}
if (rev == str)
Console.Write("Entered string is pallindrome");
else
Console.Write("Entered string is not pallindrome");
Console.ReadKey();
}
string test = "Malayalam";
char[] palindrome = test.ToCharArray();
char[] reversestring = new char[palindrome.Count()];
for (int i = palindrome.Count() - 1; i >= 0; i--)
{
reversestring[palindrome.Count() - 1 - i] = palindrome[i];
}
string materializedString = new string(reversestring);
if (materializedString.ToLower() == test.ToLower())
{
Console.Write("Palindrome!");
}
else
{
Console.Write("Not a Palindrome!");
}
Console.Read();
public static bool palindrome(string t)
{
int i = t.Length;
for (int j = 0; j < i / 2; j++)
{
if (t[j] == t[i - j-1])
{
continue;
}
else
{
return false;
break;
}
}
return true;
}
public bool Solution(string content)
{
int length = content.Length;
int half = length/2;
int isOddLength = length%2;
// Counter for checking the string from the middle
int j = (isOddLength==0) ? half:half+1;
for(int i=half-1;i>=0;i--)
{
if(content[i] != content[j])
{
return false;
}
j++;
}
return true;
}
public bool MojTestPalindrome (string word)
{
bool yes = false;
char[]test1 = word.ToArray();
char[] test2 = test1.Reverse().ToArray();
for (int i=0; i< test2.Length; i++)
{
if (test1[i] != test2[test2.Length - 1 - i])
{
yes = false;
break;
}
else {
yes = true;
}
}
if (yes == true)
{
return true;
}
else
return false;
}
public static bool IsPalindrome(string str)
{
int i = 0;
int a = 0;
char[] chr = str.ToCharArray();
foreach (char cr in chr)
{
Array.Reverse(chr);
if (chr[i] == cr)
{
if (a == str.Length)
{
return true;
}
a++;
i++;
}
else
{
return false;
}
}
return true;
}
The various provided answers are wrong for numerous reasons, primarily from misunderstanding what a palindrome is. The majority only properly identify a subset of palindromes.
From Merriam-Webster
A word, verse, or sentence (such as "Able was I ere I saw Elba")
And from Wordnik
A word, phrase, verse, or sentence that reads the same backward or forward. For example: A man, a plan, a canal, Panama!
Consider non-trivial palindromes such as "Malayalam" (it's a proper language, so naming rules apply, and it should be capitalized), or palindromic sentences such as "Was it a car or a cat I saw?" or "No 'X' in Nixon".
These are recognized palindromes in any literature.
I'm lifting the thorough solution from a library providing this kind of stuff that I'm the primary author of, so the solution works for both String and ReadOnlySpan<Char> because that's a requirement I've imposed on the library. The solution for purely String will be easy to determine from this, however.
public static Boolean IsPalindrome(this String #string) =>
!(#string is null) && #string.AsSpan().IsPalindrome();
public static Boolean IsPalindrome(this ReadOnlySpan<Char> span) {
// First we need to build the string without any punctuation or whitespace or any other
// unrelated-to-reading characters.
StringBuilder builder = new StringBuilder(span.Length);
foreach (Char s in span) {
if (!(s.IsControl()
|| s.IsPunctuation()
|| s.IsSeparator()
|| s.IsWhiteSpace()) {
_ = builder.Append(s);
}
}
String prepped = builder.ToString();
String reversed = prepped.Reverse().Join();
// Now actually check it's a palindrome
return String.Equals(prepped, reversed, StringComparison.CurrentCultureIgnoreCase);
}
You're going to want variants of this that accept a CultureInfo parameter as well, when you're testing a specific language rather than your own language, by instead calling .ToUpper(cultureInfo) on prepped.
And here's proof from the projects unit tests that it works.

Counting number of words in C#

I'm trying to count the number of words from a rich textbox in C# the code that I have below only works if it is a single line. How do I do this without relying on regex or any other special functions.
string whole_text = richTextBox1.Text;
string trimmed_text = whole_text.Trim();
string[] split_text = trimmed_text.Split(' ');
int space_count = 0;
string new_text = "";
foreach(string av in split_text)
{
if (av == "")
{
space_count++;
}
else
{
new_text = new_text + av + ",";
}
}
new_text = new_text.TrimEnd(',');
split_text = new_text.Split(',');
MessageBox.Show(split_text.Length.ToString ());
char[] delimiters = new char[] {' ', '\r', '\n' };
whole_text.Split(delimiters,StringSplitOptions.RemoveEmptyEntries).Length;
Since you are only interested in word count, and you don't care about individual words, String.Split could be avoided. String.Split is handy, but it unnecessarily generates a (potentially) large number of String objects, which in turn creates an unnecessary burden on the garbage collector. For each word in your text, a new String object needs to be instantiated, and then soon collected since you are not using it.
For a homework assignment, this may not matter, but if your text box contents change often and you do this calculation inside an event handler, it may be wiser to simply iterate through characters manually. If you really want to use String.Split, then go for a simpler version like Yonix recommended.
Otherwise, use an algorithm similar to this:
int wordCount = 0, index = 0;
// skip whitespace until first word
while (index < text.Length && char.IsWhiteSpace(text[index]))
index++;
while (index < text.Length)
{
// check if current char is part of a word
while (index < text.Length && !char.IsWhiteSpace(text[index]))
index++;
wordCount++;
// skip whitespace until next word
while (index < text.Length && char.IsWhiteSpace(text[index]))
index++;
}
This code should work better with cases where you have multiple spaces between each word, you can test the code online.
There are some better ways to do this, but in keeping with what you've got, try the following:
string whole_text = richTextBox1.Text;
string trimmed_text = whole_text.Trim();
// new line split here
string[] lines = trimmed_text.Split(Environment.NewLine.ToCharArray());
// don't need this here now...
//string[] split_text = trimmed_text.Split(' ');
int space_count = 0;
string new_text = "";
Now make two foreach loops. One for each line and one for counting words within the lines.
foreach (string line in lines)
{
// Modify the inner foreach to do the split on ' ' here
// instead of split_text
foreach (string av in line.Split(' '))
{
if (av == "")
{
space_count++;
}
else
{
new_text = new_text + av + ",";
}
}
}
new_text = new_text.TrimEnd(',');
// use lines here instead of split_text
lines = new_text.Split(',');
MessageBox.Show(lines.Length.ToString());
}
This was a phone screening interview question that I just took (by a large company located in CA who sells all kinds of devices that starts with a letter "i"), and I think I franked... after I got offline, I wrote this. I wish I were able to do it during interview..
static void Main(string[] args)
{
Debug.Assert(CountWords("Hello world") == 2);
Debug.Assert(CountWords(" Hello world") == 2);
Debug.Assert(CountWords("Hello world ") == 2);
Debug.Assert(CountWords("Hello world") == 2);
}
public static int CountWords(string test)
{
int count = 0;
bool wasInWord = false;
bool inWord = false;
for (int i = 0; i < test.Length; i++)
{
if (inWord)
{
wasInWord = true;
}
if (Char.IsWhiteSpace(test[i]))
{
if (wasInWord)
{
count++;
wasInWord = false;
}
inWord = false;
}
else
{
inWord = true;
}
}
// Check to see if we got out with seeing a word
if (wasInWord)
{
count++;
}
return count;
}
Have a look at the Lines property mentioned in #Jay Riggs comment, along with this overload of String.Split to make the code much simpler. Then the simplest approach would be to loop over each line in the Lines property, call String.Split on it, and add the length of the array it returns to a running count.
EDIT: Also, is there any reason you're using a RichTextBox instead of a TextBox with Multiline set to True?
I use an extension method for grabbing word count in a string. Do note, however, that double spaces will mess the count up.
public static int CountWords(this string line)
{
var wordCount = 0;
for (var i = 0; i < line.Length; i++)
if (line[i] == ' ' || i == line.Length - 1)
wordCount++;
return wordCount;
}
}
Your approach is on the right path. I would do something like, passing the text property of richTextBox1 into the method. This however won't be accurate if your rich textbox is formatting HTML, so you'll need to strip out any HTML tags prior to running the word count:
public static int CountWords(string s)
{
int c = 0;
for (int i = 1; i < s.Length; i++)
{
if (char.IsWhiteSpace(s[i - 1]) == true)
{
if (char.IsLetterOrDigit(s[i]) == true ||
char.IsPunctuation(s[i]))
{
c++;
}
}
}
if (s.Length > 2)
{
c++;
}
return c;
}
We used an adapted form of Yoshi's answer, where we fixed the bug where it would not count the last word in a string if there was no white-space after it:
public static int CountWords(string test)
{
int count = 0;
bool inWord = false;
foreach (char t in test)
{
if (char.IsWhiteSpace(t))
{
inWord = false;
}
else
{
if (!inWord) count++;
inWord = true;
}
}
return count;
}
using System.Collections;
using System;
class Program{
public static void Main(string[] args){
//Enter the value of n
int n = Convert.ToInt32(Console.ReadLine());
string[] s = new string[n];
ArrayList arr = new ArrayList();
//enter the elements
for(int i=0;i<n;i++){
s[i] = Console.ReadLine();
}
string str = "";
//Filter out duplicate values and store in arr
foreach(string i in s){
if(str.Contains(i)){
}else{
arr.Add(i);
}
str += i;
}
//Count the string with arr and s variables
foreach(string i in arr){
int count = 0;
foreach(string j in s){
if(i.Equals(j)){
count++;
}
}
Console.WriteLine(i+" - "+count);
}
}
}
int wordCount = 0;
bool previousLetterWasWhiteSpace = false;
foreach (char letter in keyword)
{
if (char.IsWhiteSpace(letter))
{
previousLetterWasWhiteSpace = true;
}
else
{
if (previousLetterWasWhiteSpace)
{
previousLetterWasWhiteSpace = false;
wordCount++;
}
}
}
public static int WordCount(string str)
{
int num=0;
bool wasInaWord=true;;
if (string.IsNullOrEmpty(str))
{
return num;
}
for (int i=0;i< str.Length;i++)
{
if (i!=0)
{
if (str[i]==' ' && str[i-1]!=' ')
{
num++;
wasInaWord=false;
}
}
if (str[i]!=' ')
{
wasInaWord=true;
}
}
if (wasInaWord)
{
num++;
}
return num;
}
class Program
{
static void Main(string[] args)
{
string str;
int i, wrd, l;
StringBuilder sb = new StringBuilder();
Console.Write("\n\nCount the total number of words in a string
:\n");
Console.Write("---------------------------------------------------
---\n");
Console.Write("Input the string : ");
str = Console.ReadLine();
l = 0;
wrd = 1;
foreach (var a in str)
{
sb.Append(a);
if (str[l] == ' ' || str[l] == '\n' || str[l] == '\t')
{
wrd++;
}
l++;
}
Console.WriteLine(sb.Replace(' ', '\n'));
Console.Write("Total number of words in the string is : {0}\n",
wrd);
Console.ReadLine();
}
This should work
input.Split(' ').ToList().Count;
This can show you the number of words in a line
string line = Console.ReadLine();
string[] word = line.Split(' ');
Console.WriteLine("Words " + word.Length);
You can also do it in this way!! Add this method to your extension methods.
public static int WordsCount(this string str)
{
return Regex.Matches(str, #"((\w+(\s?)))").Count;
}
And call it like this.
string someString = "Let me show how I do it!";
int wc = someString.WordsCount();

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