I wrote a do-while loop but it does not run through while condition somehow.
When I type in invalid characters it should go back to beginning and repeat as it's supposed to.
I ran the code step by step on Visual Studio and it shows that code does not even go through while condition. (no matter what the input value is)
Can someone please help me?
Many thanks in advance!
using System;
using static System.Console;
namespace a5
{
class Program
{
const string acceptedLetters = "EHLNTXZ";
static void Main(string[] args)
{
GetUserString(acceptedLetters);
ReadKey();
}
static string GetUserString(string letters)
{
string invalidCharacters;
do
{
invalidCharacters = null;
Write("Enter : ");
string inputCharacters = ReadLine();
foreach(char c in inputCharacters)
{
if(letters.IndexOf(char.ToUpper(c))==-1)
{
invalidCharacters = c.ToString();
}
}
if(invalidCharacters != null)
{
WriteLine("Enter a valid input");
}
return inputCharacters;
} while (invalidCharacters != null);
}
}
}
The problem is that you return the inputed string at the end of the loop no matter the validation done.
You can use a boolean to check this validity.
Also you don't need to parse all the string and you can break the inner loop on the first invalid char.
I renamed the string as result to use a standard pattern and to be more clean.
For example:
static string GetUserString(string letters)
{
string result;
bool isValid;
do
{
Console.Write("Enter : ");
result = Console.ReadLine();
isValid = true;
foreach ( char c in result )
if ( letters.IndexOf(char.ToUpper(c)) == -1 )
{
isValid = false;
Console.WriteLine("Enter a valid input");
break;
}
}
while ( !isValid );
return result;
}
The line return inputCharacters; makes it leave the loop.
I think you meant:
} while (invalidCharacters != null);
return inputCharacters;
using System;
using static System.Console;
namespace a5
{
class Program
{
const string acceptedLetters = "EHLNTXZ";
static void Main(string[] args)
{
GetUserString(acceptedLetters);
ReadKey();
}
static string GetUserString(string letters)
{
string invalidCharacters;
do
{
invalidCharacters = null;
Write("Enter : ");
string inputCharacters = ReadLine();
foreach(char c in inputCharacters)
{
if(letters.IndexOf(char.ToUpper(c))== -1)
{
invalidCharacters = c.ToString();
}
}
if(invalidCharacters != null)
{
WriteLine("Enter a valid input");
}
} while (invalidCharacters != null);
return inputCharacters;
}
}
}
Related
This question already has answers here:
How do I create a terminable while loop in console application?
(7 answers)
Closed 3 years ago.
I started a C# course now and there is an assignment where I have to create a "palindrome detector" program. Point is that user inputs some word or sentence, then I have to remove chars like ,.;:!? and space from it. I have done that with two different methods, because char method can not remove space so I wrote another method for it.
After "cleaning" operation program reversing input what user gave, and comparing original user input and reversed user input to each other. It they are same it prints "It is palindrome", if they are different it prints "It is not palindrome". That is working fine, BUT THE PROBLEM IS I have to put them in for loop. It have to ask input again and again, until user give empty.
This would be very easy, but somehow I can not do it.
Here is my code:
using System;
namespace Palindromi
{
class Program
{
static void Main()
{
Console.WriteLine("Hei! Tervetuloa palindromin tunnistusohjelmaan. Tämä tunnistaa, onko syöttämäsi sana sama toisinpäin!");
Console.Write("Anna teksti (tyhjä lopettaa): ");
string userinput = Console.ReadLine(); //userinput is user's input, this is what you have to modify. remove some chars and reverse it.
if (userinput == "")
{
Console.ReadLine();//when i have loop this have to be "break". This meant to break for loop when i have it.
}
char[] removechars = { '.', ':', ';', ',', '!', '?' };//this is the list of "have to be removed" chars
string userinput_without_chars = userinput.Trim(removechars); //this method remove chars which are listed
string userinput_without_chars_space = userinput_without_chars.Replace( " ", ""); //replace space with empty
string reverse_string, reversed;
reverse_string = userinput_without_chars_space;
reversed = "";
int len;
len = userinput_without_chars_space.Length - 1;
while (len >= 0)
{
reversed = reversed + reverse_string[len];
len--;
}
Console.WriteLine("Sana käännettynä on {0}", reversed); //tells user input reversed
if (userinput_without_chars_space == reversed)//check is the userinput same than reversed user input
{
Console.Write("On palindromi.");//it is palindrome
}
else
{
Console.Write("Ei ole palindromi.");//it is not palindrome
}
}
}
}
You could potentially do something along these lines:
var running = true;
while(running)
{
var input = Console.ReadLine().ToLower();
var phrase = input.Sanitize(new List<string>() {".", ",", "?", "!", "'", "&", "%", "$", " "});
if(phrase.IsPalindrome())
Console.Writeline("Input was palindrome.");
}
public static string Sanitize(this string input, IList<string> punctuation) =>
String.Join(String.Empty, input.Where(character => punctuation.Contains(character) == false));
public static bool IsPalindrome(this string sentence)
{
for (int l = 0, r = sentence.Length - 1; l < r; l++, r--)
if (sentence[l] != sentence[r])
return false;
return true;
}
public static void Close(string input)
{
// Some logic to see if the application should stop.
}
You could create another method that looks for commands, or keystrokes, then sets the boolean to run as false. Which would break the infinite loop. You could also do an abrupt close with Environment.Exit.
The very simplest approach is replace your Console.ReadLine() where you want to break to return.
Alternatively, you could wrap the logic in another while loop.
while (userinput != "")
{
// Remove chars
// rest of your logic
/* IMPORTANT */
userinput = Console.Readline();
}
To remove the symbols from the input, you can use the Regex.Replace method. In this case, you can be sure, that the specified symbols will be correctly removed from the input string. Note, that you can handle the whitespaces along with other characters you mentioned, like in the code snippet below:
var CharactersToRemove { get; set; } = " ,.;:!?";
var processedInput = Regex.Replace(input.ToLower(), $"[{CharactersToRemove}]", string.Empty);
Note, that here I used input.ToLower() to convert the input to a lowercase string. This will make the palindrome tests case-insensitive. Should you need case-sensitive palindrome tests, just remove the .ToLower() part.
There is no need to reverse the input string to check if it is a palindrome. You can check this within one for loop as follows:
bool CheckForBeingaAPalindrome(string input)
{
var frontIndex = 0;
var tailIndex = input.Length - 1;
for (; frontIndex < tailIndex;)
{
if (input[frontIndex] != input[tailIndex])
return false;
++frontIndex;
--tailIndex;
}
return true;
}
Note, that in this case you only iterate over the elements of the input string once. This approach will give you al least 4 times better performance than the one you used.
Below, you can find a complete minimal working solution to your problem.
using System.Text.RegularExpressions;
using static System.Console;
namespace Assignment
{
public static class PalindromeFinder
{
public static string CharactersToRemove { get; set; } = " ,.;:!?";
public static bool IsPalindrome(string input)
{
var processedInput = RemoveUnnecessaryCharacters(input);
return CheckForBeingAPalindrome(processedInput);
}
private static string RemoveUnnecessaryCharacters(string input)
{
return Regex.Replace(input.ToLower(), $"[{CharactersToRemove}]", string.Empty);
}
private static bool CheckForBeingAPalindrome(string input)
{
var frontIndex = 0;
var tailIndex = input.Length - 1;
for (; frontIndex < tailIndex;)
{
if (input[frontIndex] != input[tailIndex])
return false;
++frontIndex;
--tailIndex;
}
return true;
}
}
public class Program
{
private static void Main(string[] args)
{
ContinuouslyCheckUserInputForBeingAPalindrome();
}
private static void ContinuouslyCheckUserInputForBeingAPalindrome()
{
while (FetchUserInputFromConsole() is string input
&& !string.IsNullOrWhiteSpace(input))
{
var isPalindrome = PalindromeFinder.IsPalindrome(input);
var modifier = isPalindrome ? "a" : "not a";
WriteLine($"It is {modifier} palindrome");
}
}
private static string FetchUserInputFromConsole()
{
Write("Enter a string: ");
return ReadLine();
}
}
}
What I'am trying to achieve here is that when you press "1" it will check it against "code_1" and then if it matches it will say "key1 correct" and then check the other codes. But the compiler says
Cannot convert system.consolekeyinfo to string
so I'm wondering how I fix this. Here is the code that I use :
static void Main(string[] args)
{
string first_time = null;
string paktc = "Press any key to continue . . .\r\n";
string code_1 = "1";
string code_2 = "2";
string code_3 = "3";
string code_4 = "4";
if (first_time == null)
{
Console.WriteLine("\r\nYour code is 1234\r\n");
Console.WriteLine(paktc);
Console.ReadKey();
Console.WriteLine("Insert Code Now\r\n");
ConsoleKeyInfo key1 = Console.ReadKey();
if (code_1 = key1)
{
ConsoleKeyInfo key2 = Console.ReadKey();
if (code_2 = key2)
{
ConsoleKeyInfo key3 = Console.ReadKey();
if (code_3 = key3)
{
Console.WriteLine("Key3 Correct\r\n");
ConsoleKeyInfo key4 = Console.ReadKey();
if (code_4 = key4)
{
Console.WriteLine("Key4 Correct\r\n");
Console.ReadKey();
Console.WriteLine(paktc);
}
else
{
}
}
else
{
}
}
else
{
}
}
else
{
}
}
}
}
The error you are currently getting is because you forgot that:
= and == are NOT the same thing. The first is assignment, the second is comparison.
And you can't assign a string to a ConsoleKeyInfo, or vice versa, and definitely not in an if statement. Even if you had fixed that however, you still can't compare a string to a ConsoleKeyInfo. You can get its KeyChar property and compare that to a char though:
if (keyInfo.KeyChar == myString[0])
is valid (as string can be indexed to get its chars). In your case, you can just use a char and make it much simpler:
if (keyInfo.KeyChar == '1')
ToString() would work. Say we have ConsoleKeyInfo j.
It'll look like string k = j.KeyChar.ToString();
This will do exactly what you want.
So the code will look like:
ConsoleKeyInfo key1 = Console.ReadKey();
if (code_1 == key1.KeyChar.ToString())
{
//Other stuff here as follows.
}
You could even do this.
if (key1.KeyChar.ToString() == "1")
{
//Other stuff here as follows
}
Use Console.Read(); instead, it returns a int witch can be typecasted into a char. Also instead of having 4 strings with one character in them, you can have one string with the full code in it and use it as an array, See the example below
static void Main(string[] args)
{
string pw = "123";
Console.WriteLine("Enter the first digit of the password");
char toTest = (char) Console.Read();
Console.Read();
Console.Read();
if (toTest == pw[0])
{
Console.WriteLine("Enter the second digit of the password");
toTest = (char)Console.Read();
Console.Read();
Console.Read();
if (toTest == pw[1])
{
Console.WriteLine("Enter the third digit of the password");
toTest = (char)Console.Read();
Console.Read();
Console.Read();
}
}
}
The extra Console.Read(); commands are to catch the invisible characters that are inputted when pressing enter.
This is my code for some console app. First thing that doesn't work very well is method SwitchLetters. When I input some string and press enter every letter goes to new line. I don't know why. Also i don't know how to display lower and upper case in methods PrintBeforeSwitch and PrintAfterSwitch. And Exception how to use try and catch for some exception and which exception to use...
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Please input string");
string input = Console.ReadLine();
NewString ns = new NewString();
StringOperation so = new StringOperation();
ns.SwitchLetters(input);
so.PrintBeforeSwitch(input);
so.PrintAfterSwitch(input);
}
}
class NewString
{
private string newString;
public string _NewString
{
get
{
return newString;
}
set
{
newString = value;
}
}
public void SwitchLetters(string newStr)
{
StringBuilder myString = new StringBuilder();
for (int i = 0; i < newStr.Length; i++)
{
if (char.IsUpper(newStr, i))
myString.Append(char.ToLower(newStr[i]));
else if (char.IsLower(newStr, i))
myString.Append(char.ToUpper(newStr[i]));
else
myString.Append(newStr[i]);
Console.WriteLine(myString.ToString());
Console.ReadLine();
Console.WriteLine(newStr.ToUpper());
}
}
}
class StringOperation
{
private string inputString;
//public NewString newSrt;
public string InputString
{
get
{
return inputString;
}
set
{
inputString = value;
}
}
public int VocalNumber(string str)
{
int num;
return num = str.Count(a => "aeiouAEIOU".Contains(a));
}
public int SpaceNumber(string str)
{
int num;
return num = str.Count(b => b == ' ');
}
public List<int> LowerUpperCaseLattersNumber(string str)
{
int counterLower = 0;
int counterUpper = 0;
List<int> counter = new List<int>();
foreach (char value in str)
{
if (char.IsLower(value))
{
counterLower++;
}
else
{
counterUpper++;
}
}
counter.Add(counterLower);
counter.Add(counterUpper);
Console.WriteLine("Number of small latters is: {0}", counterLower);
Console.WriteLine("Number of big letters is: {0}", counterUpper);
return counter;
}
public string SwitchVocals(ref string str)
{
string vocals = str.Replace("a", "x").Replace("e", "x").Replace("i", "x").Replace("o", "x").Replace("u", "x").Replace("A", "X").Replace("E", "X").Replace("I", "X").Replace("O", "X").Replace("U", "X");
Console.WriteLine(vocals);
return vocals;
}
public void PrintBeforeSwitch(string str)
{
Console.WriteLine(str);
Console.WriteLine("Information about string:");
Console.WriteLine("Number of vowels: {0}", VocalNumber(str));
Console.WriteLine("Number of space: {0}", SpaceNumber(str));
Console.WriteLine("Number of small latters is: {0}", LowerUpperCaseLattersNumber(str));
Console.WriteLine("Number of big letters is: {0}", LowerUpperCaseLattersNumber(str));
Console.ReadLine();
}
public void PrintAfterSwitch(string str)
{
SwitchVocals(ref str);
Console.WriteLine("Information about string after switch:");
Console.WriteLine("Number of vowels: {0}", VocalNumber(str));
Console.WriteLine("Number of space: {0}", SpaceNumber(str));
Console.WriteLine("Number of small latters is: {0}", LowerUpperCaseLattersNumber(str));
Console.WriteLine("Number of big letters is: {0}", LowerUpperCaseLattersNumber(str));
Console.ReadLine();
}
}
Here is an idea how to do the exception:
public void SwitchLetters(string newStr)
{
try
{
}
catch(Exception ex)
{
Console.WriteLine(ex.ToString());
Console.ReadLine();//this stops the program so you can read the error
}
}
I think you had the two lines swapped around so.PrintBeforeSwitch and ns.SwitchLetters
static void Main(string[] args)
{
Console.WriteLine("Please input string");
string input = Console.ReadLine();
NewString ns = new NewString();
StringOperation so = new StringOperation();
so.PrintBeforeSwitch(input);
ns.SwitchLetters(input);
so.PrintAfterSwitch(input);
}
If you use Console.WriteLine("some string here"); it will do exactly as it says, write line. However you can use Console.Write("some string here"); and it should add the text/string onto the existing line.
Can you please give us more information by what you mean "First thing that doesn't work very well is method SwitchLetters..." what should it do? What does it currently do?
To resolve your issue in the comment below remove the Console.ReadLine()
public void SwitchLetters(string newStr)
{
StringBuilder myString = new StringBuilder();
for (int i = 0; i < newStr.Length; i++)
{
if (char.IsUpper(newStr, i))
myString.Append(char.ToLower(newStr[i]));
else if (char.IsLower(newStr, i))
myString.Append(char.ToUpper(newStr[i]));
else
myString.Append(newStr[i]);
Console.WriteLine(myString.ToString());
//Console.ReadLine(); This line needs to be removed
Console.WriteLine(newStr.ToUpper());
}
}
In my hangman game, I am attempting to prompt the user to enter the number of "lives" (or guesses) the player should be given. After I type a number at the prompt, the following error message is displayed:
Cannot implicitly convert type 'int' to 'string'
The following line causes the error:
lives = Console.ReadLine();
The lives field is an integer. How can I correctly assign a user-entered value to an integer field?
Here is my complete code:
using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
namespace ConsoleApplication6
{
class Hangman
{
//guesses
public static int lives = 5;
//Words for the game
static string[] wordBank = { "study", "cat", "dress", "shoes", "lipstick" };
// Create new ArrayList and initialize with words from array wordBank
static ArrayList wordList = new ArrayList(wordBank);
static void Main(string[] args)
{
Console.ForegroundColor = ConsoleColor.Green;
Console.Title = "C# Hangman";
Console.WriteLine("Hang man!");
//Gamemenu
string response = "";
do
{
Console.Write("Enter Command (1. Add Words, 2. List Words , 3. Play , 4. Exit) Pick 1-4: ");
response = Console.ReadLine();
switch (response)
{
case "1": AddWord(); break;
case "2": ListWords(); break;
case "3": Play(); break;
case "4": break;
}
} while (response != "4");
}
//add words to list
static void AddWord()
{
Console.Write("Enter the word to add: ");
String temp = Console.ReadLine();
wordList.Add(temp);
Console.WriteLine("{0} was added to the dictionary!", temp);
}
//Display words
static void ListWords()
{
foreach (Object obj in wordList)
Console.WriteLine("{0}", obj);
Console.WriteLine();
}
//How many guesses
static void AskLives()
{
try
{
Console.WriteLine("please enter number of lives?");
//This line gives me the error
lives = Console.ReadLine();
}
catch
{
// if user does not enter a number ask it again
AskLives();
}
}
//Gameplay
static void Play()
{
Random random = new Random((int)DateTime.Now.Ticks);
string wordToGuess = wordList[random.Next(0, wordList.Count)].ToString();
string wordToGuessUppercase = wordToGuess.ToUpper();
StringBuilder displayToPlayer = new StringBuilder(wordToGuess.Length);
for (int i = 0; i < wordToGuess.Length; i++)
displayToPlayer.Append('-');
List<char> correctGuesses = new List<char>();
List<char> incorrectGuesses = new List<char>();
bool won = false;
int lettersRevealed = 0;
string input;
char guess;
AskLives();
while (!won && lives > 0)
{
Console.WriteLine("Current word: " + displayToPlayer);
Console.Write("Guess a letter: ");
input = Console.ReadLine().ToUpper();
guess = input[0];
if (correctGuesses.Contains(guess))
{
Console.WriteLine("You've already tried '{0}', and it was correct!", guess);
continue;
}
else if (incorrectGuesses.Contains(guess))
{
Console.WriteLine("You've already tried '{0}', and it was wrong!", guess);
continue;
}
if (wordToGuessUppercase.Contains(guess))
{
correctGuesses.Add(guess);
for (int i = 0; i < wordToGuess.Length; i++)
{
if (wordToGuessUppercase[i] == guess)
{
displayToPlayer[i] = wordToGuess[i];
lettersRevealed++;
}
}
if (lettersRevealed == wordToGuess.Length)
won = true;
}
else
{
incorrectGuesses.Add(guess);
Console.WriteLine("Nope, there's no '{0}' in it!", guess);
lives--;
}
Console.WriteLine(displayToPlayer.ToString());
}
if (won)
Console.WriteLine("You won!");
else
Console.WriteLine("You lost! It was '{0}'", wordToGuess);
Console.Write("Press ENTER to exit...");
Console.ReadLine();
}
}
}
Your lives field is an integer, but Console.ReadLine returns a string.
You can use Int32.Parse(Console.ReadLine()) to parse the input into an integer. Note that an exception will be thrown if the text entered by the user cannot be interpreted as an integer.
Your catch block will work here and re-prompt. It would be more appropriate to use the Int32.TryParse method:
int tmpLives;
if (Int32.TryParse(Console.ReadLine(), out tmpLives))
{
lives = tmpLives;
}
else
{
AskLives();
}
You want to do something along the lines of:
string livesString = Console.ReadLine();
lives = Convert.ToInt32(livesString);
I'm guessing Console.ReadLine() gives you a string. This will not play ball with your integer lives. You could try this:
lives = Int.Parse(Console.ReadLine())
I can't figure out how to pass total, sale and comm into Main().
Anybody got an idea how to get those variables into Main and display (output) them there with the names?
Right now I can just output the variables in calcComm ...
Thanks in advance
Philip
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication38
{
class Program
{
public static void getsales()
{
string inputsales;
double total = 0;
double sale = 0;
for (int salecount = 1; salecount <= 3; ++salecount)
{
Console.WriteLine("Enter sale: ");
inputsales = Console.ReadLine();
sale = Convert.ToDouble(inputsales);
total = total + sale;
}
calcComm(total);
}
public static void calcComm(double total)
{
double comm = 0;
comm = total * 0.2;
Console.WriteLine(comm);
}
public static void Main ()
{
Console.WriteLine(" Sunshine Hot Tubs \n Sales Commissions Report\n");
char Letter;
const string name1 = "Andreas";
const string name2 = "Brittany";
const string name3 = "Eric";
string inputLetter;
string name;
Console.WriteLine("Please enter intial or type 'z' to quit");
inputLetter = Console.ReadLine();
Letter = Convert.ToChar(inputLetter);
while (Letter != 'z')
{
if (Letter == 'a')
{
name = name1;
getsales();
}
else if (Letter == 'b')
{
name = name2;
getsales();
}
else if (Letter == 'e')
{
name = name3;
getsales();
}
else
{
Console.WriteLine("Invalid entry try again");
}
Console.WriteLine("Please enter intial or type z to quit");
inputLetter = Console.ReadLine();
Letter = Convert.ToChar(inputLetter);
}
}
}
}
This gives an array of strings corresponding to the command line parameters.
Main(string [] args)
By the way, when dealing with monetary units, it's better to use decimal than double.
You should be using objects, then you can make those public.
class Sales
{
public double total;
public double sale;
public double comm;
...
public void CalcComm()
{
...
}
}
Then you can reference them like this:
Sales.total, Sales.sale
Or you can make them global but that's not normally advisable.
Look into the return keyword in C#; get your functions to return the relevant data back to main and have it make use of it.
Consider this example for how to add command line arguments. If you need them to be programmatically added consider writing a wrapper program and starting the Process inside it.
using System;
class Program
{
static void Main(string[] args)
{
if (args == null)
{
Console.WriteLine("args is null"); // Check for null array
}
else
{
Console.Write("args length is ");
Console.WriteLine(args.Length); // Write array length
for (int i = 0; i < args.Length; i++) // Loop through array
{
string argument = args[i];
Console.Write("args index ");
Console.Write(i); // Write index
Console.Write(" is [");
Console.Write(argument); // Write string
Console.WriteLine("]");
}
}
Console.ReadLine();
}
}
either you can build up a Data Transfer Object that holds all these three variables instantiate it and then return it to your main function.
You could also make use of variables that are passed as references instead of by value and use the updated reference value. Read about pass by value type & reference type for c# and the ref keyword.