C how to use enum with switch

Question

I can t figure out how to use switches in combination with an enum  Could you please tell me what I m doing wrong  and how to fix it  I have to use an enum to make a basic calculator    public enum Operator       PLUS  MINUS  MULTIPLY  DIVIDE    public double Calculate int left  int right  Operator op         int i    int  op       switch i                case 0                        return left   right                     case 1                        return left - right                     case 2                         return left   right                     case 3                        return left   right                     default                        return 0 0                      The end result should be something like this   Console WriteLine  The sum of 5 and 5 is     Calculate 5  5  PLUS   Output  The sum of 5 and 5 is 10   Could you guys please tell me how I m messing up

User · Answer

Since C  8 0 introduced a new switch expression for enums you can do it even more elegant   public double Calculate int left  int right  Operator op    gt              op switch                        Operator PLUS   gt  left   right              Operator MINUS   gt  left - right              Operator MULTIPLY   gt  left   right              Operator DIVIDE   gt  left   right                     gt   0             Ref  https   docs microsoft com en-us dotnet csharp whats-new csharp-8

User · Answer

Your code is fine  In case you re not sure how to use Calculate function  try   Calculate 5 5  Operator 0     this will add 5 5 Calculate 5 5 Operator PLUS     alternate   Default enum values start from 0 and increase by one for following elements  until you assign different values  Also you can do    public enum Operator PLUS 21 MINUS 345 MULTIPLY 98 DIVIDE 100

User · Answer

No need to convert  You can apply conditions on Enums inside a switch  Like so   public enum Operator        PLUS      MINUS      MULTIPLY      DIVIDE    public double Calculate int left  int right  Operator op        switch  op                case Operator PLUS  return left   right           case Operator MINUS  return left - right           case Operator MULTIPLY  return left   right          case Operator DIVIDE  return left   right          default  return 0 0             Then  call it like this   Console WriteLine  The sum of 5 and 5 is     Calculate 5  5  Operator PLUS

User · Answer

Two things   First  you need to qualify the enum reference in your test - rather than  PLUS   it should be  Operator PLUS    Second  this code would be a lot more readable if you used the enum member names rather than their integral values in the switch statement   I ve updated your code   public enum Operator       PLUS  MINUS  MULTIPLY  DIVIDE    public static double Calculate int left  int right  Operator op        switch  op                default          case Operator PLUS              return left   right           case Operator MINUS              return left - right           case Operator MULTIPLY              return left   right           case Operator DIVIDE              return left   right            Call this with   Console WriteLine  The sum of 5 and 5 is     Calculate 5  5  Operator PLUS

User · Answer

All the other answers are correct  but you also need to call your method correctly   Calculate 5  5  Operator PLUS     And since you use int for left and right  the result will be int as well  3 2 will result in 1   you could cast to double before calculating the result or modify your parameters to accept double

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public enum Operator               PLUS  MINUS  MULTIPLY  DIVIDE            public class Calc               public void Calculate int left  int right  Operator op                         switch  op                                case Operator DIVIDE                        Divide                     break                  case Operator MINUS                        Minus                     break                  case Operator MULTIPLY                                                break                  case Operator PLUS                                               break                  default                      throw new InvalidOperationException  Couldn t process operation      op

User · Answer

You should not cast to integer  And for the division  you need to cast left to double first  if not you will be doing an integer divide   public enum Operator       PLUS  MINUS  MULTIPLY  DIVIDE    public double Calculate int left  int right  Operator op        double sum   0 0       switch op               case Operator PLUS         sum   left   right         return sum          case Operator MINUS         sum   left - right         return sum          case Operator MULTIPLY         sum   left   right         return sum          case Operator DIVIDE         sum    double left   right         return sum          default         return sum           return sum

User · Answer

You don t need to convert it  switch op         case Operator PLUS                    your code             for plus operator         break              case Operator MULTIPLY                    your code             for MULTIPLY operator         break              default  break      By the way  use brackets

User · Answer

simply don t cast to int   switch operator               case Operator Plus           todo

User · Answer

In case you don t want to use return statement for each case  try this   Calculate int left  int right  Operator op       int result   0     switch op               case Operator PLUS                        result   left   right                       break                        return result

User · Answer

The correct answer is already given  nevertheless here is the better way  than switch    private Dictionary lt Operator  Func lt int  int  double gt  gt  operators       new Dictionary lt Operator  Func lt int  int  double gt  gt                  Operator PLUS    a  b     gt  a   b              Operator MINUS    a  b     gt  a - b              Operator MULTIPLY    a  b     gt  a   b              Operator DIVIDE   a  b     gt   double a   b            public double Calculate  int left  int right  Operator op         return operators ContainsKey  op     operators  op    left  right     0 0

[c#] C# how to use enum with switch

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