Calculator using Switch

[pinkdreammsss]

Hey guyz,
so basically user enters 3 values , 2 integer and one character that'll be used for switch case .
lets say i enter 2 and 3 and + , the output will be 2+3=5

take a look at my code :


package quiz1;
import java.util.Scanner;

public class calculator {
public static void main (String [] args){
    Scanner sc=new Scanner(System.in);
    int a,b;
    char p='+';
    char m='-';
    char multi='*';
    char div='/';
    String character;    
    
        System.out.print("enter ur firt value : ");
        a=sc.nextInt();
        System.out.print("enter ur second value : ");
        b=sc.nextInt();
        System.out.print("enter ur operator +,-,*,/ : ");
        character=sc.nextLine();
    
    
    
        switch(p){
            case '+':
                System.out.print(a+b);
                break;
            
                        
        }
    
       
    }    
}

i need to know how can i get character input from user that later would be used in switch case.
P.S: im using Scanner , i dont wanna user buffer reader.
thanks in advance.

[Tolls]

'character' is a String.
The String API has lots of methods on it, some of which return chars.
And before you ask "why don't you just tell me what I need to do", learning how to read the API and search it for useful methods is a key skill in any software development.

[pinkdreammsss]

i used string

 x=sc.next();

to get a character input from user.
it works fine for sum operator , tho for substraction it does the same function as sum , is the problem with my switch ?

package quiz1;
import java.util.Scanner;

public class calculator {
public static void main (String [] args){
    Scanner sc=new Scanner(System.in);
    int a,b;
    char p='+';
    char m='-';
    char multi='*';
    char div='/';
    String character;    
    
        System.out.print("enter ur firt value : ");
        a=sc.nextInt();
        System.out.print("enter ur second value : ");
        b=sc.nextInt();
        System.out.print("enter ur operator +,-,*,/ : ");
        character=sc.next();
    
    
    
        switch(p){
            case '+':
                System.out.print(a+b);
                break;
            
                    
        }
    switch(m){
        case 'm':
            System.out.print(a-b);
            break;
    }
       
    }    
}

[JosAH]

Print out the values for variables 'm' and 'p' and see why your code does what it does.

kind regards,

Jos

[Tolls]

I think you need to read up on how switch works.

[pinkdreammsss]

Print out the values for variables 'm' and 'p' and see why your code does what it does.

kind regards,

Jos

i dont know if i did the right thing ,

  switch(p){
            case '+':
                System.out.print(p);
                break;
            
                    
        }
    switch(m){
        case 'm':
            System.out.print(m);
            break;
    }

the out put is only + sign.

[pinkdreammsss]

i modified my switch into this :

switch(chacacter){
            case '-':
                System.out.print(a-b);
                break;
            case '+':
                System.out.print(a+b);
                break;
            case '*':
                System.out.print(a*b);
                break;
            case '/':
                System.out.print(a/b);
                break;
            default :
                System.out.print("syntax error");
                break;
                    
        }

the problem is that i dont know how to put all variables into one switch , e.g : switch(p,m,multi,div)
can u guide through this?

[JosAH]

i dont know if i did the right thing ,

  switch(p){
            case '+':
                System.out.print(p);
                break;
            
                    
        }
    switch(m){
        case 'm':
            System.out.print(m);
            break;
    }

the out put is only + sign.

So the value of variable 'm' definitely isn't 'm' (otherwise it would've been printed). Move those print statement before your switch statement and see ...

kind regards,

Jos

[pinkdreammsss]

i modified my switch into this :

switch(chacacter){
            case '-':
                System.out.print(a-b);
                break;
            case '+':
                System.out.print(a+b);
                break;
            case '*':
                System.out.print(a*b);
                break;
            case '/':
                System.out.print(a/b);
                break;
            default :
                System.out.print("syntax error");
                break;
                    
        }

the problem is that i dont know how to put all variables into one switch , e.g : switch(p,m,multi,div)
can u guide through this?

Any idea about this ?

[Tolls]

You don't put all those variables in.
You want to switch on the character the user enters (ie the first char of the 'character' string).
Each 'case' is the thing you want to check.
So your switch is almost correct, you just need to have it switching on a single character, for which you need to read the API I linked to above.

[pinkdreammsss]

you just need to have it switching on a single character

does that mean that i have to use only one character, containing all +-*/ ? probably not , cause char can only contain one value.

i know the problem is with this :

switch(m)

i need to know how to implement all of the following :

 char p='+';
    char m='-';
    char multi='*';
    char div='/';

into one switch , so when user press + or - etc...
one these cases function :

   case '-':
                System.out.print(a-b);
                break;
            case '+':
                System.out.print(a+b);
                break;
            case '*':
                System.out.print(a*b);
                break;
            case '/':
                System.out.print(a/b);
                break;

PS: didnt find what i was looking for in the API uve linked above , couldnt find anythin related to characters or strings or user input.

[Sierra]

Well I do not see the problem, maybe you should post what happens and what is the problem now - it seems the original problem was solved.

[pinkdreammsss]

Well I do not see the problem, maybe you should post what happens and what is the problem now - it seems the original problem was solved.

there's a problem with my switch , ive alredy explained why above , any idea?

[Tolls]

The value in the 'switch' is the variable you are checking.
SO you want to check the user input, not some value you have stored.
The values in the 'case' are the ones you want to compare against.
It's essentially a great big if/elseif/else statement.

switch(thingIWantToCheck) {
   case 'a': System.out.println("It's an a!");
      break;
   case 'b': System.out.prinltn("It's a b!");
      break;
   default: System.out.println("boo!");
}

Is the same as doing:

if (thingIWantToCheck == 'a') {
   System.out.println("It's an a!");
} else if (thingIWantToCheck  == 'b') {
   System.out.println("It's an b!");
} else {
   System.out.println("boo!");
}

[pinkdreammsss]

thanks for the hints guyz. the problem with my program was that i stored values as char , but the input from user was String , so i just used String for all + - * /.
here's my program :

package quiz1;
import java.util.Scanner;

public class calculator {
public static void main (String [] args){
    Scanner sc=new Scanner(System.in);
    int a,b;
    String p="+";
    String m="-";
    String multi="*";
    String div="/";
    String character;    
    
        System.out.print("enter ur firt value : ");
        a=sc.nextInt();
        System.out.print("enter ur second value : ");
        b=sc.nextInt();
        System.out.print("enter ur operator +,-,*,/ : ");
        character=sc.next();
    
    
        switch(character){
            case "-":
                System.out.print(a-b);
                break;
            case "+":
                System.out.print(a+b);
                break;
            case "*":
                System.out.print(a*b);
                break;
            case "/":
                System.out.print(a/b);
                break;
            default :
                System.out.print("syntax error");
                break;
                    
        }
   
       
    }    
}

[DarrylBurke]

I hope you're aware that switching on String was introduced in Java 7.

db

[pinkdreammsss]

I hope you're aware that switching on String was introduced in Java 7.

db

i didnt know that.

[Sierra]

Guy, you have posted so many versions of your code that it is difficult to determine which one has which problem and what actual problem you are referring to... IF you have a problem you post the code and then you answer questions to clarify what the problem is... it does barely work any other way round. Usually a "problem" has an error message or a wrong output. I do not see any of those posted here.