I've made a simple binary to decimal converter, used to work fine, I used a string variable to declare the values, but now realise I will need to store them as integers as I wanted to add in a while loop structure to validate the users choice so they could only enter 0 or 1's.
But I now have a program which says Cannot convert from 'int' to 'System.IFormatProvider'.. As I am a beginner with C#,
I have no idea what this means, and how to over come the problem, any help appreciated.. Here is my code if anyone wants to look at it:
int iBinaryNum; //To store binary number
int iDecimalNum; //To store decimal numbers
//Validation of user choice & main program
while (iBinaryNum == 0 || iBinaryNum == 1)
{
Console.WriteLine("Enter the binary number you want to convert to decimal");
iBinaryNum = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("The Binary number you have entered is " + iBinaryNum);
iDecimalNum = Convert.ToInt32(iBinaryNum, 2);
Console.WriteLine("This converted into decimal is " + iDecimalNum);
}
//If it's not equal to 0 or 1
Console.WriteLine("Invalid binary number, Please re-enter");
//Prevent program from closing
Console.WriteLine("Press any key to close");
Console.ReadKey();
iDecimalNum = Convert.ToInt32(iBinaryNum, 2);
The arguments you passed are int, int. As you can see here, you can either choose between Object, IFormatProvider, String, IFormatProvider or String, Int32.
Since the first int can only be used as Object, this means the second argument has to be IFormatProvider.
If you want a solution, you'll have to clarify what it is you're trying to do. Why do you want to convert an integer to an integer?
Convert.ToInt32(String, Int32) requires the first argument to be a String and the second an integer. You are passing two ints, which resolves to Convert.ToInt32(Object, IFormatProvider) which generates the error. You have to convert the first argument (iBinaryNum) to a String.
But I don't think your code works as you expect, since the while condition only checks if either of the ints is either 1 or 0. If the user enters 1110 it fails. Also, if the user enters anything above Int32.Max (which wouldn't be too surprising, considering how large binary numbers can grow), your program crashes. I would store the user input in a string again and check each character whether it contains valid characters (1 or 0).
Like this:
bool IsBinaryNumber(string test){
foreach(char c in test){
// If c is not either 0 or 1, break.
if(!((c=='0') || (c== '1'))){
return false;
}
}
// If everything went well, it's a binary number.
return true;
}
Complete Solution:
You can Use Regular Expressions to Check for Particular pattern in the Input String
The following program will take the Binary input from user and converts it into the decimal till the invalid value is found
string strBinaryNum=""; //To store binary number
int iDecimalNum; //To store decimal numbers
System.Text.RegularExpressions.Regex r = new System.Text.RegularExpressions.Regex("^[0-1]+$");
Console.WriteLine("Enter the binary number you want to convert to decimal");
strBinaryNum = Console.ReadLine();
while(r.Match(strBinaryNum).Success)
{
Console.WriteLine("The Binary number you have entered is " + strBinaryNum);
iDecimalNum = Convert.ToInt32(strBinaryNum, 2);
Console.WriteLine("This converted into decimal is " + iDecimalNum);
Console.WriteLine("Enter the binary number you want to convert to decimal");
strBinaryNum = Console.ReadLine();
}
Console.WriteLine("Press any key to close");
Console.ReadKey();
If you look at the different overload of Convert.ToInt32, you will see there are none that take as parameters Int32, Int32.
The overload resolution will select the one that takes object, IFormatProvider instead and 2 is an Int32, not a type that implements IFormatProvider, hence the error.
It is not clear why you are trying to convert an Int32 into an Int32 - you already have the value in iBinaryNum.
I'm not sure I really understand the problem. However here is a loop that will keep the only continue once the binary number requirements have been met.
uint iBinaryNum = 2; //To store binary number
decimal iDecimalNum; //To store decimal numbers
//Validation of user choice & main program
while (iBinaryNum > 1)
{
Console.Write("Enter the binary number you want to convert to decimal: ");
if (!uint.TryParse(Console.ReadLine(), out iBinaryNum) || iBinaryNum > 1)
{
//If it's not equal to 0 or 1
Console.WriteLine("Invalid binary number, Please re-enter");
iBinaryNum = 2;
}
}
iDecimalNum = Convert.ToDecimal(iBinaryNum);
Console.WriteLine("This converted into decimal is " + iDecimalNum);
Related
I'm doing a school assignment in which we are assigned to make a program that asks the user to input a number. It then changes the input into a number and determines if the number is an integer or a decimal. If not possible, it says this to the user. The program cannot have errors that the users input can cause.
My problem is the part where the program determines if the feed is an integer or a decimal, if I input an integer, it says the number is integer and decimal, if I input a decimal, it ends in an error. The program never reaches catch (Exception) if the input is wrong.
public static void ITellYouYourNumbers(float number)
{
try
{
float d = number;
int isInt = (int)d;
Console.WriteLine("The number is a integer");
float isFloat = (float)d;
Console.WriteLine("The number is a decimal");
}
catch (Exception)
{
Console.WriteLine("Your input cannot be changed into a number. Try again.");
Console.ReadLine();
throw;
}
}
static void Main(string[] args)
{
Console.WriteLine("Write a number");
float num = float.Parse(Console.ReadLine());
ITellYouYourNumbers(num);
}
I've tried determening the d in different ways, such as:
decimal d = number
Console.WriteLine((d % 1) == 0);
d = number
Console.WriteLine((d % 1) == 0);
and
(d % 1) < epsilon
but nothing I've tried works. If the input is integer, it shows as an integer and decimal, if I input a decimal, it says that an error occured in the float num = float.Parse(Console.ReadLine()); , but it doesn't show up as an error in the program itself.
First, float.Parse() will fail with an exception if the string you put in can not be parsed as a float (beware of the high and low limits too, there are minimum and maximum values) and the exception will not be stopped by the catch since it was not generated in the try-catch block.
Second, a float can always be casted to an int.
Third, you are casting d to a float while d is already a float so why would it not work ?
Fourth, you are putting your float parameter (called "number") in another float inside the function (called "d"). While not wrong technically speaking, it bothers me to duplicate a value when you have no plan to modify either instance of it.
If you can modify the main, call directly your ITellYouYourNumbers function and put the string in without trying to parse it. If I understand the instructions of your exercise correctly, all you have to do is check that
1/ The string is not empty even after removing all blank characters at both ends.
2/ After trimming, it contains only numbers and at most one '.' or ',' character.
3/ If it contains a '.' or ',', it is a decimal. Otherwise, it is an integer.
If you are actually supposed to cast the input as a number, you can check if it represents an integer by exploiting the fact that int x = (int)y will get the integer part of y and put it in x.
After that, you just have to check whether x==y or not.
I need a console app that changes the sign to a certain typed number. You type 10, it gives you -10. And so on. I've managed to do that, but I can't do it if I type 1.5 for example. Or any decimal number.
I get "Input string was not in a correct format".
this is what I did.
string inputData = Console.ReadLine();
int a = Convert.ToInt32 (inputData);
int b = a * (-1);
Console.WriteLine(b);
Console.ReadLine();
You need to use decimal as a variable type if you want to work with decimal numbers
If so, use Convert.ToDecimal instead of ToInt32
You don't really need to use multiplication here, it's enough just to use -a instead
string inputData = Console.ReadLine();
decimal a = Convert.ToDecimal (inputData);
decimal b = -a;
Console.WriteLine(b);
Console.ReadLine();
The code below restricts everything I need restricted, but it allows the user to input more than 1 decimal point
if (System.Text.RegularExpressions.Regex.IsMatch(txtOperand2.Text,
"[^0-9],[.],[\b]"))
{
MessageBox.Show("Please enter only numbers.");
txtOperand2.Text = txtOperand2.Text.Remove(txtOperand2.Text.Length - 1);
}
As per #DourHighArch's worthy comment. If you are just checking for a valid decimal to a certain number of places, and you want a fast culture aware solution (and other configurability like number styles).
Instead of regex, you could do something like this. decimal.TryParse and checking how many decimal places it has via some means.
Converts the string representation of a number to its Decimal
equivalent. A return value indicates whether the conversion succeeded
or failed.
Given
// gets the decimal places by deconstruction
public static int GetDecimalPlaces(decimal d)
=> BitConverter.GetBytes(decimal.GetBits(d)[3])[2];
Usage
if (decimal.TryParse(argument, out var d) && GetDecimalPlaces(d) == 1)
Console.WriteLine("You win, play again?");
Add pepper and salt to taste
I have an assignment for TAFE in which i have to create a console program in Visual Studio that calculates the cost of a consultation based on consultation time (at $25 an hour).
string hours, rate, total;
Console.Write("Enter consultation time in hours");
hours = Console.ReadLine();
rate = ;
total = hours * rate;
Console.WriteLine("Fee is " + total);
My problem is on line 5, I get the error "operator '*' cannot be applied to operands of type 'string' and 'string;"
Can someone explain to me what is wrong, why 2 strings cant be multiplied and also supply an alternate method of getting that line to work?
EDIT: Thank you everyone. All info given was helpful. I've completed it leaving the rate as an Integer as its a set value not changed by user input, the hours and total are still strings, The hours converting to decimal via the convert.ToDecimal line GianlucaBobbio gave me. The only problem now is console doesnt stay open after calculating rate * hour, but i can fix that.
You may just have a new regular user :D! appreciate the help. you're all life savers :)
You're looking for a numeric type like int or decimal. You'll need to parse those from the input.
Console.ReadLine() returns a string so naturally, you can't multiply a string with a number. You have to parse the string as a double/int/float/decimal (whatever the case is) and then do the multiplication.
One example would be:
double hours = 0.0;
if(double.TryParse(Console.ReadLine(),out hours))
{
total = (decimal)hours * rate;
Console.WriteLine("Fee is " + total);
}
else
Console.WriteLine("You did not enter a valid number of hours.");
Since this is a calculation about money, your rate and total variables should be of type decimal.
You should convert both strings to decimal, so you can multiple them and finally convert them to string again. So you can use de Convert method.
string hours, rate, total;
Console.Write("Enter consultation time in hours");
hours = Console.ReadLine();
rate = ;
total = Convert.ToString(Convert.ToDecimal(hours) * Convert.ToDecimal(rate));
Console.WriteLine("Fee is " + total);
To handle if he puts a valid number you can use decimal.TryParse(string, decimal) which returns a bool value, and if the string is a decimal value it'll be in the out variable like decimal
string hours, rate, total;
Console.Write("Enter consultation time in hours");
hours = Console.ReadLine();
rate = ;
decimal hourInput = 0;
if(!decimal.TryParse(hours, out hourInput)
{
Console.Write("Thats not a number!");
}
else
{
total = Convert.ToString(hourInput * Convert.ToDecimal(rate));
Console.WriteLine("Fee is " + total);
}
Sorry for my bad english
C#'s type system doesn't allow for a lot of inference; unlike JavaScript or Ruby, for example, it won't implicitly convert strings to numeric types when you attempt to perform arithmetic on them. Instead, you must explicitly convert the user's input from a String to some numeric type. Here's one approach:
string hours;
decimal numericHours, rate, total;
Console.Write("Enter consultation time in hours");
hours = Console.ReadLine();
if (!Decimal.TryParse(hours, out numericHours))
{
Console.WriteLine(String.Format("{0} doesn't appear to be a valid number of hours. Please enter a numeric value.", hours));
}
else
{
rate = 35.6;
total = numericHours * rate;
Console.WriteLine("Fee is " + total);
}
That if statement deserves some further explanation: Decimal.TryParse() is one of the rare methods in the .NET framework that has two effects: it returns true or false depending on whether the first parameter can be successfully parsed as data of type decimal. The second parameter, decorated with the out keyword, will contain the resulting decimal value if the parse was successful.
A couple of bonus .NET tips: Notice the use of String.Format() to control the insertion of variables into strings - I find it nicer to use than the + string-concatenation operator. Also, as other answers have pointed out, arithmetic is performed somewhat differently on double and decimal types, due to different binary representations. When dealing with precise fractional values, especially monetary, prefer the decimal type.
I've been trying to understand how one would input an integer and have a function return the digits in base 10 in C#. I've researched around and can't find many code examples to work with other than the math formulas.
Thanks!
It sounds like you just want:
int value = 2590123;
string text = value.ToString();
That will automatically use base 10... at least in all the cultures I'm aware of. If you really want to make sure, use the invariant culture:
string text = value.ToString(CultureInfo.InvariantCulture);
Note that the concept of a base only makes sense when you talk about some representation with separate "digits" of some form - such as a string representation. A pure number doesn't have a base - if you have 16 apples, that's the same number as if you've got 0x10 apples.
EDIT: Or if you want to write a method to return the sequence of digits as integers, least significant first:
// Note that this won't give pleasant results for negative input
static IEnumerable<int> GetDigits(int input)
{
// Special case...
if (input == 0)
{
yield return 0;
yield break;
}
while (input != 0)
{
yield return input % 10;
input = input / 10;
}
}
Making a whole lot of assumptions, I'm guessing you want something like this:
// All ints are "base 10"
var thisIsAlreadyBase10 = 10;
Console.WriteLine("The number {0} in base 10 is {0}", thisIsAlreadyBase10);
// However, if you have a string with a non-base 10 number...
var thisHoweverIsAStringInHex = "deadbeef";
Console.WriteLine(
"The hex string {0} == base 10 int value {1}",
thisHoweverIsAStringInHex,
Convert.ToInt32(thisHoweverIsAStringInHex, 16));