How can I make a calculator ask the user if they want to perform another calculation in Java?-CodePudding

I have tried to do this using a do while loop however the variable isn't found. My goal is to basically perform the code all over again when the user wants to. Can anybody help?

import java.util.Scanner;
public class Calculator {
    public static void main(String args[]) {
        do{
            Scanner typed=new Scanner(System.in);
            System.out.println("Please type: 1 for add, 2 for subtract, 3 for multiply or 4 for divide");
            int userInput=typed.nextInt();
            System.out.println("Please enter the first number to calculate:");
            double number1=typed.nextDouble();
            System.out.println("Please enter the second number to calculate:");
            double number2=typed.nextDouble();
            if (userInput==1){
                System.out.println("The answer is");
                double result=number1 number2;
                System.out.println(result);
            }
            if (userInput==2){
                System.out.println("The answer is");
                double result=number1-number2;
                System.out.println(result);
            }
            if (userInput==3){
                System.out.println("The answer is");
                double result=number1*number2;
                System.out.println(result);
            }
            if (userInput==4){
                System.out.println("The answer is");
                double result=number1/number2;
                System.out.println(result);
            }
                System.out.println("Do you want to perform another calculation? Press 1 for yes or 2 for no.");
                int pressed=typed.nextInt();
            
        }while(pressed==1);
            
    }
}

CodePudding user response：

You're trying to use a variable outside of its scope.

    do{
      // ...
      int pressed=typed.nextInt();
        
    }while(pressed==1);  // Outside of the scope of 'pressed'

You can address this by moving the declaration outside the loop, but leaving the assignment.

    int pressed = 1;

    do{
      // ...
      pressed=typed.nextInt();
        
    }while(pressed==1);  // Outside of the scope of 'pressed'

CodePudding user response：

pressed leaves scope after the body of your loop. Move the declaration of pressed to before the do.

int pressed = 0;
do {
    // ...
    pressed=typed.nextInt();
} while(pressed==1);

Or, you could change your loop to an infinite loop while(true); and use

int pressed = typed.nextInt();
if (pressed != 1) {
    break; // End the infinite loop
}

CodePudding user response：

Just declare 'pressed' variable outside the do while loop. Write 'int pressed' before "do {" line and remove int from "int pressed=typed.nextInt();" this line(i.e. pressed=typed.nextInt();)