Hey I´am trying to add two numbers together via switch case.
I have 3 inputs, number 1 and number 2. The 3rd input is the method which I´d like to calculate number 1 and 2 with(e.g +, -, *, /, etc...)
Now the problem is how do I create something like "this" ? I´ve tried this way, but it does not work...
Is it possible to make switch case like this : case %: ???
Thanks
string firstNumber;
string secondNumber;
string method;
//get numbers
Console.WriteLine ("Get first number");
firstNumber = Console.ReadLine ();
Console.WriteLine ("get 2nd number");
secondNumber = Console.ReadLine ();
Console.WriteLine ("the method to calculate with");
Console.WriteLine (" 1:\"*\"");
Console.WriteLine (" 2:\"/\"");
Console.WriteLine (" 3:\"+\"");
Console.WriteLine (" 4:\"-\"");
method = Console.ReadLine ();
//convert
int methodNew = Convert.ToInt32 (method);
int firstNumberNew = Convert.ToInt32 (firstNumber);
int secondNumberNew = Convert.ToInt32 (secondNumber);
switch (methodNew) {
case 1:
firstNumberNew *= secondNumberNew;
break;
default:
Console.WriteLine ("check the methods.");
break;
}
Console.WriteLine (methodNew);
Of course, you can read in a char and do a switch-case
for it:
int c = Console.Read(); // read from console
switch(c) {
case '/':
// work
break;
case '%':
// work
break;
case '*':
// work
break;
case '+':
// work
break;
}
First get the operator then use switch like this:
char method = Console.ReadKey().KeyChar;
double result = 0.0;
switch (method)
{
case '+':
result = firstNumberNew + secondNumberNew;
break;
case '-':
result = firstNumberNew - secondNumberNew;
break;
case '/':
result = firstNumberNew / secondNumberNew;
break;
case '%':
result = firstNumberNew % secondNumberNew;
break;
default:
Console.WriteLine("Invalid value, try again");
break;
}
Console.WriteLine(result);
It would be better if you change the type of firstNumberNew and secondNumberNew to double.Alşo you can use a while loop to force user to enter a valid character.
Related
The Console.Writeline(result); at the end returns error CS0165 Use of unassigned local variable 'result' and I don't know why. Would appreciate an explanation as I'm a complete beginner. Like I said in the title, I'm trying to build a calculator.
char Operator;
double firstNumber;
double secondNumber;
Console.WriteLine("Enter the first number");
string firstNumberAsText = Console.ReadLine();
Console.WriteLine("Enter the second number");
string secondNumberAsText = Console.ReadLine();
Console.WriteLine(#"Enter a math operation. '+' for addition, '-' for subtraction, '*' for multiplication, '/' for division, '%' for remainder and '^' for power");
string mathOperator = Console.ReadLine();
firstNumber = Convert.ToDouble(firstNumberAsText);
secondNumber = Convert.ToDouble(secondNumberAsText);
Operator = Convert.ToChar(mathOperator);
double result;
switch (Operator)
{
case '+':
result = firstNumber + secondNumber;
break;
case '-':
result = firstNumber - secondNumber;
break;
case '*':
result = firstNumber * secondNumber;
break;
case '/':
result = firstNumber / secondNumber;
break;
case '%':
result = firstNumber % secondNumber;
break;
case '^':
result = Math.Pow(firstNumber, secondNumber);
break;
default:
Console.WriteLine("unrecognised operator: " + Operator);
break;
}
Console.WriteLine(result);
Console.ReadKey();
The error itself tells you what's wrong:
Error CS0165: Use of unassigned local variable 'result'
This means that you're trying to use a variable that may not have been initialized yet. Notice that it isn't initialized it when it's declared, and it isn't assigned a value in the default: case in the switch statement.
So there are two ways to solve this:
1) Initialize the variable when you declare it
double result = 0;
2) Or, make sure every possible code path (including then default switch case) assigns a value to it before it's used
default:
result = 0;
Console.WriteLine($"unrecognised operator: {Operator}");
break;
In the case of an unrecognised operator, the result variable would be undefined when trying to do the Console.WriteLine(). You either need to set it to a value when catching the default behaviour, or initialize it before the switch.
} else {
int indexGenerator = numberGenerator.Next(1, 4);
int answer1 = finalUserInput - theCorrectAnswer;
switch (indexGenerator) {
case 1:
Console.WriteLine("You are off by" + answer1);
case 2:
Console.WriteLine("So close. Maybe if you add or subtract " + answer1 + "?");
When I try to get the switch to work, an error message pops up saying Control Case Cannot Fall Through From Case1 to Another.
You need to add break; at the end of each case in your switch statement.
switch (indexGenerator) {
case 1:
Console.WriteLine("You are off by" + answer1);
break;
case 2:
Console.WriteLine("So close. Maybe if you add or subtract " + answer1 + "?");
break;
}
The problem here is that you forgot to add break;'s to your code. Your code should read as follows.
switch (indexGenerator){
case 1:
Console.WriteLine("You are off by" + answer1);
break;
case 2:
Console.WriteLine("So close. Maybe if you add or subtract " + answer1 + "?");
break;
}
The purpose of having the break is to basically tell your program that you are breaking away from that case: portion of the statement.
You need a break at the end of the case 1 block:
}
else
{
int indexGenerator = numberGenerator.Next(1, 4);
int answer1 = finalUserInput - theCorrectAnswer;
switch (indexGenerator)
{
case 1:
Console.WriteLine("You are off by" + answer1);
break; // missing break
case 2:
Console.WriteLine("So close. Maybe if you add or subtract " + answer1 + "?");
break; // missing break
Add one at the end of your case 2 block as I've shown too.
I've been working on this issue for awhile and I've been stuck so I hope someone can push me in the right direction. I have a c# console application that will take in a string and verify that it contains only 0-9, a-z, A-Z, and -.
My issue that I'm having is that I need to convert any letters in the phone number to their respective number. So if I input 1800-Flowers, it will output as 1800-3569377. I have my methods defined:
I'm not looking for the solutions here (this is homework), but I'm looking for a push in the right direction. Do I need to convert the string to a char array to break up each individual character, and then use that in the convert method to switch any letter into a number?
There are certainly a lot of solutions here. Since you're already using Regex, you could approach it in a basic way:
num = Regex.Replace(num, #"[abcABC]", "2");
num = Regex.Replace(num, #"[defDEF]", "3");
//....
or you could create a Dictionary<string,char> and run through each char and convert it to the mapped character. Something like :
var dict = new Dictionary<string, char>();
dict.Add("abcABC",'2');
//...
foreach(char c in num.Where(char.IsLetter))
{
var digit = dict.First(d => d.Key.Contains(c)).Value;
num = num.Replace(c, digit);
}
Like you said, the LINQ here is splitting the string to a char array, and looping through ones that are letters
Since this is for school, i'm sure you can't go crazy with more advanced topics. Lets keep it simple with a switch/case.
You can map the letters to their corresponding number first, just use a switch/case to find the correct number depending on the letter.
For example:
String phoneNumber = "1800ab";
for(int x=0; x < phoneNumber.Length; x++)
{
if(Char.IsLetter(phoneNumber[x]))
{
switch(phoneNumber[x].ToString().ToLower())
{
case "a":
case "b":
case "c":
//This is number 2!
break;
}
}
}
String already implements IEnumerable<char> - so no need to "break up" there.
Mapping of something to something (like letter code to matching number) is generally done with map (associative array) types (in C#/.Net it is Dictionary) that provide mapping one value ("key") to corresponding "value" - consider using that.
string letter1 = AskuserforInput("first letter");
string number1 = SwitchMethod(letter1);
string letter2 = AskuserforInput("second letter");
string number2 = SwitchMethod(letter2);
string letter3 = AskuserforInput("third letter");
string number3 = SwitchMethod(letter3);
string letter4 = AskuserforInput("fouth letter");
string number4 = SwitchMethod(letter4);
string letter5 = AskuserforInput("fifth letter");
string number5 = SwitchMethod(letter5);
string letter6 = AskuserforInput("sixth letter");
string number6 = SwitchMethod(letter6);
string letter7 = AskuserforInput("seventh letter");
string number7 = SwitchMethod(letter7);
string letter8 = AskuserforInput("eigth letter");
string number8 = SwitchMethod(letter8);
string letter9 = AskuserforInput("ninth letter");
string number9 = SwitchMethod(letter9);
string letter10 = AskuserforInput("tenth letter");
string number10 = SwitchMethod(letter10);
//declaring strings
Console.WriteLine("This is the original letter phone digits");
Console.WriteLine("({0}{1}{2})) {3}{4}{5} - {6}{7}{8}{9} ", letter1,letter2, letter3, letter4, letter5, letter6, letter7, letter8, letter9, letter10);//continue this
Console.WriteLine("The actual numbers" );
Console.WriteLine("({0}{1}{2})) {3}{4}{5} - {6}{7}{8}{9} ", number1, number2, number3, number4, number5, number6, number7, number8, number9, number10);//continue this
Console.Read();
#region End Program
//wait for program to acknowledge results
Console.BackgroundColor = ConsoleColor.White;
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("\n\nPlease hit ENTER to end program. . .");
Console.Read();
#endregion
Console.Read();
//also pulled this back up from a previous program
}
public static string SwitchMethod(string x)
{
string y = "*";
switch (x)
{
case "0":
y = "0";
break;
case "1":
y = "1";
break;
case "A":
case "a":
case "B":
case "b":
case "C":
case "c":
case "2":
y = "2";
break;
case "D":
case "d":
case "E":
case "e":
case "F":
case "f":
case "3":
y = "3";
break;
case "G":
case "g":
case "H":
case "h":
case "I":
case "i":
case "4":
y = "4";
break;
case "J":
case "j":
case "K":
case "k":
case "L":
case "l":
case "5":
y = "5";
break;
case "M":
case "m":
case "N":
case "n":
case "O":
case "o":
case "6":
y = "6";
break;
case "P":
case "p":
case "Q":
case "q":
case "R":
case "r":
case "S":
case "s":
case "7":
y = "7";
break;
case "T":
case "t":
case "U":
case "u":
case "V":
case "v":
case "8":
y = "8";
break;
case "W":
case "w":
case "X":
case "x":
case "Y":
case "y":
case "Z":
case "z":
case "9":
y ="9";
break;
default:
Console.WriteLine("knucklehead, not a letter");
Console.WriteLine("an '*' will show up");
break;
//used cases, next will use to.lower
//Lynch helped
}
return y;
}
public static string AskuserforInput(string x)
{
Console.WriteLine("\nPlease type {0}", x);
String input = Console.ReadLine();
return input;
}
I'm sure someone can think of a better way, but you could loop through each digit and pass it to this function:
int Asc(char ch)
{
//Return the character value of the given character
return (int)Encoding.ASCII.GetBytes(ch)[0];
}
Then just assign a number based on which ASCII character is returned.
Hi what have I done wrong, I'm getting the error "Control cannot fall through from one case label to another" at line 15 (Switch (z))
using System;
namespace test
{
class MainClass
{
public static void Main (string[] args)
{
Console.WriteLine ("Velkommen til pCalc! Vælg hvad du skal I menuen:");
Console.WriteLine ("1. Phythagoras");
Console.WriteLine ("2. Cirklens areal og omkreds");
Console.WriteLine ("3. + - * eller /");
int z = Convert.ToInt32(Console.ReadLine());
switch (z)
{
case 1:
Console.WriteLine ("Her skal du angive 2 værdier, a og b for at beregne c");
Console.WriteLine ("Skriv a værdien: ");
double a = double.Parse (Console.ReadLine ());
Console.Clear ();
Console.WriteLine ("Skriv værdien for b: ");
double b = double.Parse (Console.ReadLine ());
Console.Clear ();
Console.WriteLine (Math.Sqrt((Math.Pow(a, 2))+(Math.Pow(b, 2))));
break;
case 2:
Console.WriteLine ("Skriv radius a cirklen: ");
double r = double.Parse (Console.ReadLine ());
double areal = (Math.Pow (r, 2) * Math.PI);
Console.Clear ();
Console.WriteLine (areal);
Console.WriteLine ("Vil du også vide omkredsen? Skriv 1 for Ja, 2 for Nej");
int q = Convert.ToInt32 (Console.ReadLine ());
switch (q) {
case 1:
Console.WriteLine (r * 2 * Math.PI);
break;
case 2:
break;
}
}
}
}
}
You have to terminate every case (even the last one!) with a break statement. Specifically in your case:
case 2:
Console.WriteLine ("Skriv radius a cirklen: ");
double r = double.Parse (Console.ReadLine ());
double areal = (Math.Pow (r, 2) * Math.PI);
Console.Clear ();
Console.WriteLine (areal);
Console.WriteLine ("Vil du også vide omkredsen? Skriv 1 for Ja, 2 for Nej");
int q = Convert.ToInt32 (Console.ReadLine ());
switch (q) {
case 1:
Console.WriteLine (r * 2 * Math.PI);
break;
case 2:
break;
}
break; // ← mandatory!
One clarification here.
Answers here show you must have a break, and that is mostly true except in one coding case. If the "break" is unreachable, then it's not required and leaving it out quiets the compiler warning.
Consider if a case "returns" either directly or through a series of conditionals.
<code>
case 1:
if (Red) { return 6;} else {return 10;}
case 2:
if (Blue) {return 4;} else {return 50;}
Both conditional conditions must return (or break, I suppose) but as long as all code streams get you out of the switch, the compiler is fine with it.
I have strings in a XML file that ment to be doubles (or float) such as:
<VIPair>
<voltage>+100mV</voltage>
<current>+1.05pA</current>
</VIPair>
<VIPair>
<voltage>+5.00mV</voltage>
<current>+0.0035nA</current>
</VIPair>
The first pair will be "0.1" Volt and "0.00000000000105" Ampere.
The second pair would be "0.005" Volt and "0.000000000035" Ampere.
How can I convert them to double of float in C#?
Thanks.
P.S: I already can read them from xml file and at the moment I retrive them as string.
Try with this:
// Read string (if you do not want to use xml)
string test = "<voltage>+100mV</voltage>";
string measure = test.Substring(test.IndexOf('>')+1);
measure = measure.Substring(0, measure.IndexOf('<')-1);
// Extract measure unit
string um = measure.Substring(measure.Length - 1);
measure = measure.Substring(0, measure.Length - 1);
// Get value
double val = Double.Parse(measure);
// Convert value according to measure unit
switch (um)
{
case "G": val *= 1E9; break;
case "M": val *= 1E6; break;
case "k": val *= 1E3; break;
case "m": val /= 1E3; break;
case "u": val /= 1E6; break;
case "n": val /= 1E9; break;
case "p": val /= 1E12; break;
}
Hi here is another version of what Marco has written.
string str = "1pV";
double factor;
double value;
switch (str[str.Length-2])
{
case 'M': factor = 1E6; break;
case 'm': factor = 1E-3; break;
case 'n': factor = 1E-9; break;
case 'p': factor = 1E-12; break;
default:
factor = 1; break;
}
value = double.Parse(str.Substring(0,str.Length-2)) * factor;
Assuming that the html text is already available to you. I have tried to do the same thing with one substring, switch case with characters instead of strings(This is a bit faster to comparing strings) and a double.parse. Hope someone comes up with a better version than this.
Remove the suffix string mV and nA using string.Substring or string.Remove() method and use double.TryParse() method to parse string to double.
If your values always have 2 chars on the end you could simple remove these and parse the number.
var newstring = fullstring.Substring(0, fullstring.Length - 2);
var number = double.Parse(newstring);