I need to output the value of d using the same Console.WriteLine. But i am only getting Result not the value of d in output. In what way i can achieve this?
namespace ConsoleApplication2
{
class Program
{
static void Main(string[] args)
{
int a;
int b;
Console.WriteLine("Please Enter the first Digit");
a = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Please Enter the Second Digit");
b = Convert.ToInt32(Console.ReadLine());
int d = a + b;
Console.WriteLine("Result",(d));
}
}
}
Use:
Console.WriteLine("Result {0}", d);
You are using this overload.
UPDATE
If you look at the link above, you can read how it works. In short, first you specify the formatting, where {0} references the first value of the param object-array, {1} references the second value of the param object-array, etc. After the format, you give the objects to use.
So in your case, you need a single value, which means two arguments, a format, and a value. Hence "Result {0}" with d, which will become (when for example d=10) "Result 10".
Note: also removed the unnecessary parenthesis.
Use
Console.WriteLine("Result {0}", d);
Related
I'm trying to make a little multiplication only calculator.
I'm trying to do
int a;
a = Console.ReadLine();
and then it tell me cannot implicitly convert string to int.
I'd like it to readline my int variable and multiply it together with another int variable but its not letting me.
Thank you
namespace ConsoleApp9
{
class Program
{
static void Main(string[] args)
{
int a;
int b;
Console.WriteLine("Hey I'm a calculator in training and I'd like to test out my skills with you.");
Console.WriteLine("I can only do one type of equation right now but I'm still learning");
Console.WriteLine("What will your first number be?");
a = Console.ReadLine();
Console.WriteLine("So youre first number is ");
Console.Write(a);
Console.WriteLine(" Alrighty then what is your second number ?");
b = Console.ReadLine();
Console.WriteLine(a);
Console.WriteLine("*");
Console.WriteLine(b);
Console.WriteLine("=");
Console.WriteLine(a * b);
}
}
}
Method
Console.ReadLine();
actually returns string. Whereas variable of type int only stores integers not string representation of integers. So you need to convert your input from string to int. Since there is no implicit conversion from string to int, so you need to convert explicitly. You can do this like this
int a = Convert.ToInt32(Console.ReadLine()); OR
int a = int.Parse(Console.ReadLine()); OR
int a = (int) Console.ReadLine();
There are other ways as well. For details visit How to: Convert a String to a Number (C# Programming Guide)
I have a successful clean code that does a conversion of Celcius to Fahrenheit using Double.Parse. However, I was curious on how it would look if I did a Double.TryParse but I can't seem to figure out how to complete the code. Once executed, I am able to present "Invalid Code", in my "if, else" but I still get this after my Invaild Output...
Please enter a value for conversion:
30x
Invalid code
The conversion from Celcius to Fahrenheit is: 32
using System;
using System.Text;
namespace CSharpBasics
{
class Program
{
public static double CelciusToFarenheit(string celciusTemperature)
{
//Converting string to a double for conversion
double celcius;
if (Double.TryParse(celciusTemperature, out celcius))
{
}
else
{
Console.WriteLine("Invalid code");
}
double fahrenheit = (celcius * 9 / 5) + 32;
return fahrenheit;
}
public static void Main(string[] args)
{
Console.WriteLine("Please enter a value for conversion:");
var input = CelciusToFarenheit(Console.ReadLine());
Console.WriteLine("The conversion from Celcius to Fahrenheit is: " + input);
}
}
}
You should verify your input before the conversion to make sure you never display invalid result for an invalid input but return a message notifying the wrong input first. Something like this:
public static double CelciusToFarenheit(double celcius)
{
double fahrenheit = (celcius * 9 / 5) + 32;
return fahrenheit;
}
public static void Main(string[] args)
{
Console.WriteLine("Please enter a value for conversion:");
var input = Console.ReadLine();
double celcius;
if (Double.TryParse(input, out celcius))
{
var result = CelciusToFarenheit(celcius);
Console.WriteLine("The conversion from Celcius to Fahrenheit is: " + result);
}
else
{
Console.WriteLine("Invalid code");
}
}
The method signature public static double CelciusToFarenheit(...) says that this method returns a value - and currently it does.
However, your program flow has to consider invalid input - and thus you need 2 information:
was the entered value a valid value
what's is the value
There are different methods to solve this issue, at least the following:
return a struct or object that holds both information
use the return value and indicate invalid results with exceptions
split the single method into 2 methods, one for checking validity and one for delivering the value.
Let's discuss the 3 options:
3) This might be looking nice, but when you look at Double.TryParse(), you'll likely introduce duplicate code. And when you look at the Main method, the abstraction level will not be the same.
2) Exceptions shall be used for exceptional cases. Wrong user input seems to be a rather usual thing. Not ideal for this case.
1) Sounds quite ok, except that the method might be responsible for 2 things: checking validity and calculating.
To implement that, you don't even need to write a new struct or class. You can simply use Nullable<double> or double?.
Since you're talking about clean code (potentially referring to R.C. Martin), I would start by looking at the main method. Basically I would say the code follows the IPO principle (input, processing, output). However, one line does 2 things:
var input = CelciusToFarenheit(Console.ReadLine());
Also, the variable name input is not so useful here, because it's not the input of the user, but the output after processing.
Proposal for that part:
public static void Main(string[] args)
{
var userInput = GetCelsiusInputFromUser();
var output = CelciusToFarenheit(userInput);
PrintOutput(output);
}
Also, the conversion method does not only convert, but print partial results as well:
Console.WriteLine("Invalid code");
I'd remove that piece and leave it to the output method to handle that case.
Full code:
using System;
namespace CSharpBasics
{
class Program
{
public static double? CelciusToFarenheit(string celciusTemperature)
{
//Converting string to a double for conversion
double celcius;
if (Double.TryParse(celciusTemperature, out celcius))
{
double fahrenheit = (celcius * 9 / 5) + 32;
return fahrenheit;
}
else
{
return null;
}
}
public static void Main(string[] args)
{
var userInput = GetCelsiusInputFromUser();
var output = CelciusToFarenheit(userInput);
PrintOutput(output);
}
private static void PrintOutput(double? output)
{
if (output == null)
{
Console.WriteLine("Invalid code");
}
else
{
Console.WriteLine("The conversion from Celcius to Fahrenheit is: " + output);
}
}
private static string GetCelsiusInputFromUser()
{
Console.WriteLine("Please enter a celsius value for conversion:");
var userInput = Console.ReadLine();
return userInput;
}
}
}
BTW: if you don't have a technical issue, https://codereview.stackexchange.com/ might be better suited for questions regarding clean code.
Ahoy! I have just started methods but I am a tad confused when it comes to methods with math. First post so be nice :) I'm aware I out in NumberToSquare way too many times!
Write a program that asks the user to enter a number. In your program write a function called SquareValue that takes an integer parameter and calculates the square of integer parameter and returns this squared value. Your program should take this returned square value and display it. An example of the output is:
Please enter a number to square: 8
/ 8 squared is: 64
What I have so far is not so comprehensible. I thought along a few different avenues and was unsure as to what to delete. Help please.
namespace SquareValue
{
class Program
{
static void Main(string[] args)
{
int number=NumberToSquare();
SquareValue(NumberToSquare * NumberToSquare);
string output;
Console.ReadKey();
}
public int SquareValue(NumberToSquare, NumberToSquare);
{
int result = NumberToSquare * NumberToSquare;
return result;
Console.WriteLine("{0} squared is "+result");
}
public int NumberToSquare()
{
Console.WriteLine("Please enter a number to square: ");
int NumberToSquare = Console.ReadLine();
return NumberToSquare;
}
}
I see no reason to over complicate this:
public int Square(int x)
{
return (x * x);
}
or
public int Square(int x)
{
return Math.Pow(x,2);
}
Or just use Math.Pow as it exists with 2 as the Power Of number.
You seem very green on programming and I'm not sure SO is a place to go to learn the basics, but I'll run through what you've done and explain what's going wrong.
Your original program concept is fine but there are many issues with basic syntax. I understand you mightn't be familiar with reading compiler errors so I'll explain the errors that I see just reading through the code...
You put a ; at the end of the SquareValue(..., ...) method which teeminates the declaration so the body in braces isn't part of the method, then things go haywire later on.
You're not passing in the value captured from the NumberToSquare method...
int number=NumberToSquare();
SquareValue(NumberToSquare * NumberToSquare);
NumberToSquare isn't a defined variable so NumberToSquare * NumberToSquare can't calculate, what you'd want is number * number where `number is the value entered by the user.
Your definition of int SquareValue(NumberToSquare, NumberToSquare) expects two parameters although you haven't speified the type. It should be
int SquareValue(int NumberToSquare, int NumberToSquare)
but you have the same variable declared twice which is another error and then you aren't passing two parameters anyway. You want to multiply a number by itself therefore you only have a single source number so why declared two parameters? You need a single parameter method
int SquareValue(int NumberToSquare)
and call like this
int number=NumberToSquare();
SquareValue(number);
Now the SquareValue() method returns an int but you never capture it in the calling code and display the result in the method. Follow the idea in this app that the Main method will do all the orchestration and display, but the SquareValue() method should ONLY do a calculation and not any I/O. I'd also rename the NumberToSquare() method a as what is actually happening ... GetNumberToSquareFromUser().
And there's also a stray " before the closing bracket.
Console.WriteLine("{0} squared is " + result");
And you defined a string output variable which is never used.
And your methods need to be static because main(..) is a static method, not instance. If you declare a Squaring class and instantiated it then you could call non static methods from that.
Also ReadLine() returns a string which can't be assigned to an int.
And finally the result line is implicitly using String.Format behind the scenes but you haven't specified the original number for the {0} token. You could also use interpolation. You could do either of these
Console.WriteLine("{0} squared is " + result, number);
Console.WriteLine($"{number} squared is " + result);
So here's your program revised
class Program
{
static void Main(string[] args)
{
int number = GetNumberToSquareFromUser();
int result = SquareValue(number);
Console.WriteLine("{0} squared is " + result, number);
Console.ReadKey();
}
public static int SquareValue(int numberToSquare)
{
return numberToSquare * numberToSquare;
}
public static int GetNumberToSquareFromUser()
{
Console.WriteLine("Please enter a number to square: ");
int NumberToSquare = int.Parse(Console.ReadLine());
return NumberToSquare;
}
}
I hope this help, I know it's alot to take in, but I hope you take the time to read and really understand rather than just blindly submit the revised version.
When writing your methods, make them reusable. When you start using a method to output to the console in addition to its primary purpose (i.e. to square a number), its re-usability becomes minimal. It is much better to keep specific code in your main method, and put sub tasks into separate methods, such as squaring a number. Now, whenever you need to square a number, you already have a perfectly good method for that.
I didn't handle the case for users entering bad input, but that can be done in the else of the TryParse if block.
static void Main(string[] args)
{
int squredNum = 0;
int NumberToSquare = 0;
Console.WriteLine("Please enter a number to square: ");
if(int.TryParse(Console.ReadLine(), out NumberToSquare))
{
squredNum = SquareValue(NumberToSquare);
Console.WriteLine("{0} squared is {1}", NumberToSquare, squredNum);
}
Console.ReadKey();
}
static int SquareValue(int numberToSquare)
{
return numberToSquare * numberToSquare;
}
p.s. I would not recommend using Math.Pow() to square a number. No need to kill a fly with a bazooka!
Here is an example of such program with robust handling:
using System;
namespace ConsoleApp1
{
internal static class Program
{
private static void Main(string[] args)
{
while (true)
{
Console.WriteLine("Enter value to square or X to exit");
var line = Console.ReadLine();
if (line == null)
continue;
if (line.Trim().Equals("X", StringComparison.InvariantCultureIgnoreCase))
{
Console.WriteLine("Exitting ...");
break;
}
int result;
if (!int.TryParse(line, out result))
continue;
Console.WriteLine(result * result);
}
}
}
}
See the docs online, understand each statement, write your very own program then as your teacher will likely figure out you didn't pull that solely by yourself :)
I am attempting to write a recursion code that computes the factorial from a given number. (Factorial of 3 is "3*2*1 = 6"). I have written the following code, and the following error message is printed
"Invalid token '(' in class, struct, or interface member declaration"
I have checked my code and in my eyes, I can't see an error, is there anything I can do to fix the issue? The c# code is posted below.
(ps. I'm not a c# wizz.)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
namespace Rextester
{
public class Program
{
public static void Main(string[] args)
{
int num1;
int num2;
int num3 = 0;
Console.WriteLine("Insert number");
num1 = Console.ReadLine();
num2 = num1 -1;
factorial(num1, num2, num3);
Console.WriteLine("Your number is {0}", factorial());
}
Console.ReadKey();
static int factorial(int a, int b, int c)
{
if (a > 0)
{
a * b = c;
factorial(a - 1, c, c);
return c;
}
}
}
}
You have Console.ReadKey(); outside method declaration. Move it into public static void Main(string[] args) and it will work.
It wont like Console.WriteLine("Your number is {0}", factorial());
Your factorial function has 3 parameters, you've never declared one with none.
You need to keep the result and display it.
If you are interested, there are also ways to improve the actual factorial routine you've got too
There are a number of problems with your code, and it does not compile, lets go through each error
Invalid token '(' in class, struct, or interface member declaration
This, as pointed out in the other answers is the Console.Readkey() in the middle of your class outside of any method. Move it into the bottom of the Main method.
Cannot implicitly convert type 'string' to 'int'
This is due to the line num1 = Console.ReadLine(); as that method returns a string and you're trying to assign it to an int. The right way to deal with this is to check the user input, to ensure they have typed a number. For brevity I'll do it the wrong and just assume its right.
num1 = int.Parse(Console.ReadLine()); // Use TryParse here, and notify the user if they typed something wrong
No overload for method 'factorial' takes 0 arguments
This is because you've tried to call your factorial method with no arguments. I think you were trying to output the result from the call above.
var result = factorial(num1, num2, num3);
Console.WriteLine("Your number is {0}", result);
The type or namespace name 'a' could not be found (are you missing a using directive or an assembly reference?)
This is due to this line: a * b = c; which just doesn't make sense. I assume you meant c = a * b;
Finally
'Rextester.Program.factorial(int, int, int)': not all code paths return a value
You need to return a value outside the if of factorial. Here you then get into an endless loop, but at least your code compiles! Now just fix your algorithm. This is much simpler
static int factorial(int n)
{
if(n == 1)
return 1;
return factorial(n-1) * n;
}
Live example: http://rextester.com/OUCC98161
I'm obviously a newbie when it comes to C# and the following program is from a Charles Petzold book that I don't fully understand. The parameter in the GetDouble method is a string named prompt. Nowhere is this declared and I think that's what's messing me up. I see that the Main method is calling GetDouble and is printing three strings to the console, but this whole thing looks weird to me. Is this typical programming design, or is this not industry standard, but for purposes of showing how things can be done? The book doesn't give an answer either way. My fledgling programming self wouldn't pass a string to the Main method. Can someone help straighten me out?
using System;
class InputDoubles
{
static void Main()
{
double dbase = GetDouble("Enter the base: ");
double exp = GetDouble("enter the exponent: ");
Console.WriteLine("{0} to the power of {1} is {2}", dbase, exp, Math.Pow(dbase, exp));
}
static double GetDouble(string prompt)
{
double value = Double.NaN;
do
{
Console.Write(prompt);
try
{
value = Double.Parse(Console.ReadLine());
}
catch
{
Console.WriteLine();
Console.WriteLine("you enter an invalid number!");
Console.WriteLine("please try again");
Console.WriteLine();
}
}
while (Double.IsNaN(value));
return value;
}
}
Nowhere is this declared and I think that's what's messing me up.
Wait, it's declared right there - in the header of the method:
static double GetDouble(string prompt)
// ^^^^^^^^^^^^^ This is the declaration of prompt
prompt is different from other variables that you have seen in that it is not a normal variable: it is a formal parameter of a method.
Unlike regular variables which you initialize and assign explicitly with the assignment operator =, formal parameters are assigned implicitly by virtue of calling a method. When you call the method, you pass it an expression with the actual parameter, which acts as an assignment of that expression to the formal parameter. Imagine that the prompt variable is assigned "Enter the base: " before the first call, and then it is assigned "enter the exponent: " before the second call to understand what is going on when you call GetDouble.
The GetDouble(string) method does just that - it gets a double from the input.
The text that is prompted to the user is a parameter, because there are two different values to be entered: first the base number, second the exponent.
By making the prompt a parameter, the GetDouble(string) method can handle everything from prompting the user for input to returning the value.
The alternative would be to prompt the user outside of GetDouble(string). Which of these two options is preferable is a matter of taste.
Oh, and as you've probably figured by now, this has nothing to do with the exception handling in the method.
You can change it this way. It does the same but I think more understandable:
static void Main()
{
string messageForDbaseParam="Enter the base: ";
double dbase = GetDouble(messageForDbaseParam);
string messageForExpParam ="enter the exponent: ";
double exp = GetDouble(messageForExpParam);
Console.WriteLine("{0} to the power of {1} is {2}", dbase, exp, Math.Pow(dbase, exp));
}
static double GetDouble(string prompt)
{
double value = Double.NaN;
Boolean incorrectValue=true;
while(incorrectValue)
{
Console.Write(prompt);
try
{
value = Double.Parse(Console.ReadLine());
incorrectValue=false;
}
catch
{
Console.WriteLine("error");
}
}
return value;
}