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Thread: Problem with calcylator.

  1. #1
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    Default Problem with calcylator.

    Hey

    Iīm trying to make a calcylator in java. First you write the first number, then the second number and then the unit(+,-/ or *). But i only get lots of errors the whole time and i canīt see my problem.
    Hereīs my code
     import java.util.Scanner;
     
    class KO{
        public static void main(String args[]){
    	     Scanner Alexander = new Scanner(System.in);
    		 double fnum, snum, unit, answer;
    		 System.out.println("Write fnum: ");
    		 fnum = Alexander.nextDouble();
    		 System.out.println("write snum: ");
    		 snum = Alexander.nextDouble();	
    		 System.out.println("+,-,/,*: ");
    		 unit = Alexander.nextDouble();	
    		  if (unit = +) { 
    		  answer = fnum + snum;
    		  }if (unit = -) {
             answer = fnum - snum;		  
    		  System.out.println(answer);
    		}  
    	}	 
    }

    And the errors is.

    calculator2.java:13; error: illegal start of expression
    if (unit = +) {

    calculator2.java:15: error illegal start of expression
    } if (unit = -) {

    Sincrerly
    JustACode


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Problem with calcylator.

    i only get lots of errors
    Please copy the full text of the error messages and paste it here.

    Please edit your post and wrap your code with
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Problem with calcylator.

    Quote Originally Posted by Norm View Post
    Please copy the full text of the error messages and paste it here.

    Please edit your post and wrap your code with
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.
    Fixed it.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Problem with calcylator.

    if (unit = +) {
    Two things wrong with the syntax here:
    = is the assignment operator, == is for testing equality
    + is the addition operator. If you wanted a String, enclose it in "s like this: "+"

    What is the purpose of that statement?
    unit is a numeric variable of type double
    Are you trying to compare its value to something?
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: Problem with calcylator.

    This is what iīm trying to do. When you start the program, the text "Enter first number" will be shown. Then you write some numbers and press enter. The text "Enter second number" will be shown. Write some numbers ad click enter the text "choose a unit" will be show. This is here my problem. I have problems to make that if you choose +, sum is fnum + snum = answer, if you choose * the sum is fnum * snum, if you choose - the sum is fnum - snum and if you choose / the sum is fnum / snum.

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: Problem with calcylator.

    Did you change the code to read the arithmetic operators as Strings and not as numbers?
    If you don't understand my answer, don't ignore it, ask a question.

  7. #7
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    Default Re: Problem with calcylator.

    Quote Originally Posted by Norm View Post
    Did you change the code to read the arithmetic operators as Strings and not as numbers?
    What exactly do you mean i should do?

  8. #8
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    Default Re: Problem with calcylator.

    You're reading in your +-*/ with nextDouble() but none of those are doubles.
    Writing code is your job, helping you fix and understand it is mine.

    <-- Be sure to thank and REP (Star icon) those who have helped you. They appreciate it!

  9. #9
    Super Moderator Norm's Avatar
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    Default Re: Problem with calcylator.

    Read the API doc for the Scanner class to find a method that reads a String.
    Java Platform SE 7
    If you don't understand my answer, don't ignore it, ask a question.

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