so I am trying to make a multiplication table with c#, and I want that when user give a wrong input in code it should not start the program from start but just ask to re-enter that value. when I run this code and put wrong input. it will ask to display the multiplication table again. but I want that if I give wrong input at "start value" then it will only ask for re-entering the start value but not the whole input
public void Multi()
{
Console.Write("\n\n");
bool tryAgain = true;
while (tryAgain)
{
try
{
Console.Write("Display the multiplication table:\n ");
int t = Convert.ToInt16(Console.ReadLine());
Console.WriteLine("\n");
Console.WriteLine(" Start value ");
Console.WriteLine("\n");
Console.WriteLine(" End value \n");
int end = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("\n");
SwapNum(ref start, ref end);
Console.Write("\n");
Console.WriteLine("Display the table\n");
int i = start;
do
{
Console.WriteLine(t + " * " + i + " = " + t * i);
//Console.WriteLine("{0} * {1} = {2}", t, i, t*i);
i++;
} while (i <= end);
}
catch (Exception ex)
{
Console.WriteLine("Please Enter the inter number ");
}
}
}
static void SwapNum(ref int x, ref int y)
{
if (x >= y)
{
int temp = x;
x = y;
y = temp;
}
}
Change Parse into TryParse; let's extract a method for this
private static int ReadInt(string prompt) {
while (true) {
Console.WriteLine(prompt);
int result;
if (int.TryParse(Console.ReadLine(), out result))
return result;
Console.WriteLine("Sorry, it's not a correct integer value, please try again.");
}
}
...
public void Multi() {
Console.Write("Display the multiplication table:\n ");
// Now we keep asking user until the correct value entered
int t = ReadInt("Start value");
...
}
Related
I'm trying to restart my program after I catch an error using the catch() function, but I also want it to display the error, stop the rest of the program from running, and restart the program.
This is just a shortened version of my code which I have used as an example.
using System;
namespace Calculator
{
internal class Program
{
private static void Main(string[] args)
{
float input = 0;
while (input != 5)
{
Console.Clear();
Console.WriteLine("What would you like to do? Type: 1 for Addition. Write 5 to end program.");
try
{
input = float.Parse(Console.ReadLine());
}
catch (FormatException)
{
Console.WriteLine("Please enter a number");
}
//Addition
if (input == 1)
{
Console.WriteLine("Enter First Value: ");
string FirstValue = Console.ReadLine();
float firstval = 0;
try
{
firstval = float.Parse(FirstValue);
}
catch (FormatException)
{
Console.WriteLine("Please enter a number");
break;
}
Console.WriteLine("Enter Second Value: ");
string SecondValue = Console.ReadLine();
float secval = 0;
try
{
secval = float.Parse(SecondValue);
}
catch (FormatException)
{
Console.WriteLine("Please enter a number");
break;
}
float sum = Add(firstval, secval);
Console.WriteLine("The sum is: {0}", sum);
}
}
}
public static float Add(float num1, float num2)
{
return num1 + num2;
}
}
}
When it says
catch (FormatException)
{
Console.WriteLine("Please enter a number");
break;
}
The break; makes it so the rest of the code stops, and it displays the error. That is good, but the program also ends after that, what I want, is that the program repeats after error. Is there any way that this could happen, but it allows 1) the Console.WriteLine("Please enter a number");, 2) the program to not run the rest of the code (The part where we are asked for a second value), and 3) the program to restart for the beginning. Please let me know if that didn't make sense, as it was a hard to explain. :)
It is very simple you do not need the "break" keyword because "break" terminates the loop execution to continue execution on exception use "continue" keyword without quotes the working fiddle is here
and your code after replacing "break" with "continue" is following
using System;
namespace Calculator
{
public class Program
{
public static void Main(string[] args)
{
float input = 0;
while (input != 5)
{
Console.Clear();
Console.WriteLine("What would you like to do? Type: 1 for Addition. Write 5 to end program.");
try
{
input = float.Parse(Console.ReadLine());
}
catch (FormatException)
{
Console.WriteLine("Please enter a number");
}
//Addition
if (input == 1)
{
Console.WriteLine("Enter First Value: ");
string FirstValue = Console.ReadLine();
float firstval = 0;
try
{
firstval = float.Parse(FirstValue);
}
catch (FormatException)
{
Console.WriteLine("Please enter a number");
continue;
}
Console.WriteLine("Enter Second Value: ");
string SecondValue = Console.ReadLine();
float secval = 0;
try
{
secval = float.Parse(SecondValue);
}
catch (FormatException)
{
Console.WriteLine("Please enter a number");
continue;
}
float sum = Add(firstval, secval);
Console.WriteLine("The sum is: {0}", sum);
}
}
}
public static float Add(float num1, float num2)
{
return num1 + num2;
}
}
}
I'm new to c# and am trying to make a simple calculator.
It works fine until it goes back to the start to take a new number.
When taking the new number it says it cant convert the user input to a integer.
using System;
namespace simpleCalculator
{
class MainClass
{
public static void Main(string[] args)
{
start:
Console.Clear();
Console.WriteLine("Enter first number");
int x = Convert.ToConsole.ReadLine();
Console.WriteLine("Would you like to\n1. Add\n2. Multiply\n3. Devide");
string o = Console.ReadLine();
if (o == "1")
{
Console.WriteLine("Enter second number\n");
int y = Convert.ToInt32(Console.ReadLine());
add(temp, y);
goto start;
Console.Clear();
goto start;
}
}
public static void add(int num01, int num02)
{
Console.Clear();
Console.WriteLine((num01 + num02) + "\nPress enter to contiue.");
Console.Read();
}
}
}
Use TryParse so if the parsing fails, you will not get an exception.
var enteredValue = Console.ReadLine();
var parsedValue;
if (!int.TryParse(enteredValue, out parsedValue))
{
// parse failed do whatever you want
}
Do that for both entries and if both of them pass, then call your add method.
You're looking for int.Parse(). Be careful to validate your input. You should probably create an escape condition.
Edited to show an alternative solution
Edited to be more explicit on how to handle some input
class Program
{
public static void Main(string[] args)
{
string input = String.Empty;
int x = 0, y = 0;
while (true)
{
try
{
Console.WriteLine("Enter first number");
x = int.Parse(Console.ReadLine());
Console.WriteLine("Would you like to\n1. Add\n2. Multiply\n3. Divide");
input = Console.ReadLine();
Console.WriteLine("Please enter a second number");
y = int.Parse(Console.ReadLine());
}
catch
{
Console.WriteLine("Invalid input");
continue;
}
switch (input)
{
case "1":
Console.WriteLine($"{x} + {y} = " + add(x, y));
break;
case "2":
//TODO implement multiply case
break;
case "3":
//TODO implement divide case
break;
default:
Console.WriteLine("Invalid input");
break;
}
}
}
public static int add(int x, int y) => x + y;
}
Try this:
int numbers = Convert.ToInt32("1234");
i want to restrict user to just enter integers and if user enters any alphabet or string characters it should display error in c#
Console.WriteLine("enter a");
int a = int.Parse(Console.ReadLine());
Console.WriteLine("enter b");
int b = int.Parse(Console.ReadLine());
Program e = new Program();
int sum= e.sum( a, b);
Console.WriteLine("sum is " + sum);
public int sum(int a, int b)
{
int sum = a + b;
return sum;
}
use this only if you want to check condition for integer
string strValue = Convet.toString("YourValue");
if(int.TryParse(strValue , out value))
{
}
else
{
//Value is Not Integer.
}
string a = Console.ReadLine();
string b = Console.ReadLine();
int inputnumber1 = 0;
int inputnumber2= 0;
if (int.TryParse(a,out inputnumber1))
{
}
like that
you can do a try catch:
try
{
Console.WriteLine("enter a");
string a = Console.ReadLine();
Console.WriteLine("enter b");
string b = Console.ReadLine();
a=int.parse(a);
b=int.parse(b);
Program e = new Program();
int sum= e.sum( a, b);
Console.WriteLine("sum is " + sum);
public int sum(int a, int b)
{
int sum = a + b;
return sum;
}
}
catch(FormatException e){Console.WriteLine("Wrong input");}
or you can also do something like this to get the user input and repeat the ask to get the parameters if it fails:
Boolean wrongInput=true;
string read;
int a;int b;
while(wrongInput)
{
Console.WriteLine("enter a");
read = Console.ReadLine();
bool isNumeric = int.TryParse(read, out a);
if(isNumeric){wrongInput=false;}
}
wronginput=while(wrongInput)
{
Console.WriteLine("enter b");
read = Console.ReadLine();
bool isNumeric = int.TryParse(read, out b);
if(isNumeric){wrongInput=false;}
}
You could do a check before you parse the input to int.
string input = Console.Readline();
if(IsInt(input))
int a = int.Parse(input);
else
//Error message here
private bool IsInt(string in)
{
string intChars = "0123456789";
return in.All(intChars.Contains);
}
Another option would be to use int.TryParse(), see https://msdn.microsoft.com/de-de/library/f02979c7(v=vs.110).aspx on that.
here i ask the user for homework scores which are then averaged after discarding the smallest and largest score. i have stored the user input in an array. in my DisplayResults method im not sure how to display the lowest and highest scores that were discarded. any help is appreciated! Here is what i have so far:
class Scores
{
static void Main(string[] args)
{
double sum = 0;
double average = 0;
int arraySize;
double[] inputValues;
arraySize = HowManyScores();
inputValues = new double[arraySize];
GetScores(inputValues);
sum = CalculateSum(inputValues);
average = CaculateAverage(sum, arraySize);
DisplayResults(inputValues, average);
Console.Read();
}
public static int HowManyScores()
{
string input;
int size;
Console.WriteLine("How many homework scores would you like to enter?");
input = Console.ReadLine();
while (int.TryParse(input, out size) == false)
{
Console.WriteLine("Invalid data. Please enter a numeric value.");
input = Console.ReadLine();
}
return size;
}
public static void GetScores(double[] inputValues)
{
double scoreInput;
Console.Clear();
for (int i = 0; i < inputValues.Length; i++)
{
scoreInput = PromptForScore(i + 1);
inputValues[i] = scoreInput;
}
}
public static double PromptForScore(int j)
{
string input;
double scoreInput;
Console.WriteLine("Enter homework score #{0}:", j);
input = Console.ReadLine();
while (double.TryParse(input, out scoreInput) == false)
{
Console.WriteLine("Invalid Data. Your homework score must be a numerical value.");
input = Console.ReadLine();
}
while (scoreInput < 0)
{
Console.WriteLine("Invalid Data. Your homework score must be between 0 and 10.");
input = Console.ReadLine();
}
while (scoreInput > 10)
{
Console.WriteLine("Invalid Data. Your homework score must be between 0 and 10.");
input = Console.ReadLine();
}
return scoreInput;
}
public static double CalculateSum(double[] inputValues)
{
double sum = 0;
for (int i = 1; i < inputValues.Length - 1; i++)
{
sum += inputValues[i];
}
return sum;
}
public static double CaculateAverage(double sum, int size)
{
double average;
average = sum / ((double)size - 2);
return average;
}
public static void DisplayResults(double[] inputValues, double average)
{
Console.Clear();
Console.WriteLine("Average homework score: {0}", average);
//Console.WriteLine("Lowest score that was discarded: {0}",
//Console.WriteLine("Highest score that was discarded: {0}",
}
}
}
You basically only have to do one thing: Sorting the array after you received your input data. Then, printing the first and last value gives you the minimal and maximal score. Use
Array.Sort(intArray);
in main after calling GetScores and
Console.WriteLine("Lowest score: {0} Highest score: {1}",
inputValues[0], inputValues[inputValues.Length - 1]);
to print the results. Cheers
EDIT: The proposal by Jens from the comments using the Min/Max is probably more what you're looking for if you're not interested in complete ordering of your values.
The program I've written is set to only accept positive integers as input. If the user inputs a letter instead, then it crashes. Negative integers don't cause any problems, though it's not 'valid' in regards to how my program functions.
What I want to do is:
Prevent the program from crashing from invalid input.
Display an error message if the input is invalid
Have the program continue where it left off, without affecting the rest of the program.
Also, a part of my program involves division. Is there a way to prevent the user from entering all zeros?
This is in C#
My code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace OverallCalculator
{
class Program
{
static void Main(string[] args)
{
bool shouldContinue;
do
{
Console.WriteLine("Enter Striking Level: ");
string striking = Console.ReadLine();
Console.WriteLine("Enter Grappling Level: ");
string grappling = Console.ReadLine();
Console.WriteLine("Enter Submission Level: ");
string submission = Console.ReadLine();
Console.WriteLine("Enter Durability Level: ");
string durability = Console.ReadLine();
Console.WriteLine("Enter Technical Level: ");
string technical = Console.ReadLine();
Console.WriteLine("Enter Speed Level: ");
string speed = Console.ReadLine();
Console.WriteLine("Enter Hardcore Level: ");
string hardcore = Console.ReadLine();
Console.WriteLine("Enter Charisma Level: ");
string charisma = Console.ReadLine();
int gra = Convert.ToInt32(grappling);
int str = Convert.ToInt32(striking);
int dur = Convert.ToInt32(durability);
int spd = Convert.ToInt32(speed);
int tec = Convert.ToInt32(technical);
int hdc = Convert.ToInt32(hardcore);
int cha = Convert.ToInt32(charisma);
int sub = Convert.ToInt32(submission);
int total = str + gra + sub + dur + tec + spd + cha + hdc;
int overall = total / 8 + 8;
Console.WriteLine("The Overall is " + overall);
Console.WriteLine("Do you wish to continue? y/n? ");
if (Console.ReadLine() == "y")
{
shouldContinue = true;
}
else break;
} while (shouldContinue == true);
}
}
}
int value = 0;
if (!int.TryParse(input, out value))
{
MessageBox.Show("Oops");
} else {
// use the value in the variable "value".
}
static void Main(string[] args)
{
bool validInput = false;
string inputString;
UInt32 validPositiveInteger = 0;
while (!validInput)
{
Console.WriteLine("Please enter a positive 32 bit integer:");
inputString = Console.ReadLine();
if (!UInt32.TryParse(inputString, out validPositiveInteger))
{
Console.WriteLine("Input was not a positive integer.");
}
else if (validPositiveInteger.Equals(0))
{
Console.WriteLine("You cannot enter zero.");
}
else
{
validInput = true;
//Or you could just break
//break;
}
}
Console.WriteLine(String.Format("Positive integer = {0}", validPositiveInteger));
}
Here you go:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace OverallCalculator
{
class Program
{
static void Main(string[] args)
{
bool shouldContinue = true;
while (shouldContinue)
{
int strikingLevel = GetValue("Enter Striking Level: ");
int grapplingLevel = GetValue("Enter Grappling Level: ");
int submissionLevel = GetValue("Enter Submission Level: ");
int durabilityLevel = GetValue("Enter Durability Level: ");
int technicalLevel = GetValue("Enter Technical Level: ");
int speedLevel = GetValue("Enter Speed Level: ");
int hardcoreLevel = GetValue("Enter Hardcore Level: ");
int charismaLevel = GetValue("Enter Charisma Level: ");
int total = strikingLevel + grapplingLevel + durabilityLevel + submissionLevel +
technicalLevel + speedLevel + charismaLevel + hardcoreLevel;
int overall = total / 8 + 8;
Console.WriteLine("\nThe Overall is {0}.", overall);
while (true)
{
Console.WriteLine("Do you wish to continue? y/n? ");
string response = Console.ReadLine();
if (response.Equals("y", StringComparison.CurrentCultureIgnoreCase) ||
response.Equals("yes", StringComparison.CurrentCultureIgnoreCase))
{
shouldContinue = true;
break;
}
else if (response.Equals("n", StringComparison.CurrentCultureIgnoreCase) ||
response.Equals("no", StringComparison.CurrentCultureIgnoreCase))
{
shouldContinue = false;
break;
}
}
}
}
private static int GetValue(string prompt)
{
while (true)
{
Console.WriteLine(prompt);
string input = Console.ReadLine();
int value;
if (int.TryParse(input, out value))
{
if (value <= 0)
Console.WriteLine("Please enter a positive number.");
else
return value;
}
else
{
Console.WriteLine("Please enter a number.");
}
}
}
}
}
Yes... before you do anything calculations, you need to validate the data you are going to use. If any data is incorrect, then you display a messagebox detailing the errors and return focus to the form so the user can fix the errors. Repeat as necessary.
I wrote this one many moons ago when I first learned C#. It is a conversion from a VB function that I got back in VB5 days. The major benefit of the function is that there is no error - an input will just not allow any characters outside of the predefined list.
/***********************************************************************
* bool ValiText(char inChar,
* string valid,
* bool editable,
* bool casesensitive
* Description: Validate Input Characters As They Are Input
* Notes: For each control whose input you wish to validate, just put
* e.Handled = ValiText(e.KeyChar, "0123456789/-" [,true][,true])
* In The KeyPress Event
***********************************************************************/
public bool ValiText(char inChar, string valid, bool editable, bool casesensitive)
{
string inVal = inChar.ToString();
string tst = valid;
/// Editable - Add The Backspace Key
if (editable) tst += ((char)8).ToString();
/// Case InSensitive - Make Them Both The Same Case
if (!casesensitive)
{
tst = tst.ToLower();
inVal = inVal.ToLower();
}
return tst.IndexOf(inVal,0,tst.Length) < 0;
}
public bool ValiText(char inChar, string valid, bool editable)
{
string tst = valid;
/// Editable - Add The Backspace Key
if (editable) tst += ((char)8).ToString();
return tst.IndexOf(inChar.ToString(),0,tst.Length) < 0;
}
public bool ValiText(char inChar, string valid)
{
return valid.IndexOf(inChar.ToString(),0,valid.Length) < 0;
}
Note That This Will Not Work On A Web APP.