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Thread: my program for calculating the circumference and area isn't working

  1. #1
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    Default my program for calculating the circumference and area isn't working

    Here is the program I wrote for calculating the circumference of a circle

    //circumference.java
    //program that calculates the area and circumference of a circle

    import java.util.Scanner; //program uses class scanner

    public class circumference{

    //main method begins execution of Java application

    public static void main(String args[]){

    //create scanner to obtain input from the command line

    Scanner input = new Scanner(System.in);

    double a; //declares Area
    double c; //declares circumference

    double r; //declares the radius

    System.out.printf("Enter the radius"); //prompt
    r=input.nextInt(); //read first number the user

    c=2*3.14*r;

    System.out.printf("The circumference is",c); //display circumference;

    }//end method main

    }//end class circumference
    Even though my code compiles and runs without any errors, the program doesn't calculate the circumference.


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    Default Re: my program for calculating the circumference and area isn't working

    System.out.printf("The circumference is",c); //display circumference;
    Where do you print the circumference? Perhaps read the API for this method...
    PrintStream (Java Platform SE 7 )
    ...or use System.out.print to print out the value.

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    Default Re: my program for calculating the circumference and area isn't working

    Actually, I wanted to add when I add %d\n in the line of my code that displays the circumference, I get a large error message when I run the code.

    --- Update ---

    Here is what my code now looks like :"
    //circumference.java
    //program that calculates the area and circumference of a circle

    import java.util.Scanner; //program uses class scanner

    public class circumference{

    //main method begins execution of Java application

    public static void main(String args[]){

    //create scanner to obtain input from the command line

    Scanner input = new Scanner(System.in);

    double a; //declares Area
    double c; //declares circumference

    double r; //declares the radius

    System.out.print("Enter the radius"); //prompt
    r=input.nextInt(); //read first number the user

    c=2*3.14*r;

    System.out.printf("The circumference is %d\n",c); //display circumference;

    }//end method main

    }//end class circumference
    Even though my code compiles correctly, when I run it and it ask me to enter a value for the radius, I get a large error message. I can't displayed the error message here because the windows command line will not allow me to copy my error message

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    Default Re: my program for calculating the circumference and area isn't working

    Welcome to the forum! Please read this topic to learn how to post code in code or highlight tags and other useful info for new members.

    Please post your code in code tags per the above link.

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    Default Re: my program for calculating the circumference and area isn't working

    Quote Originally Posted by GregBrannon View Post
    Welcome to the forum! Please read this topic to learn how to post code in code or highlight tags and other useful info for new members.

    Please post your code in code tags per the above link.
    Okay I will repost my last post :


    Actually, I wanted to add when I add %d\n in the line of my code that displays the circumference, I get a large error message when I run the code.

    --- Update ---

    Here is what my code now looks like :

     
    //circumference.java
    //program that calculates the area and circumference of a circle
     
    import java.util.Scanner; //program uses class scanner
     
    public class circumference{
     
    //main method begins execution of Java application
     
    public static void main(String args[]){
     
    //create scanner to obtain input from the command line
     
    Scanner input = new Scanner(System.in);
     
    double a; //declares Area
    double c; //declares circumference
     
    double r; //declares the radius
     
    System.out.print("Enter the radius"); //prompt
    r=input.nextInt(); //read first number the user
     
    c=2*3.14*r;
     
    System.out.printf("The circumference is %d\n",c); //display circumference;
     
    }//end method main
     
    }//end class circumference

    Even though my code compiles correctly, when I run it and it ask me to enter a value for the radius, I get a large error message. I can't displayed the error message here because the windows command line will not allow me to copy my error message

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    Member Ada Lovelace's Avatar
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    Default Re: my program for calculating the circumference and area isn't working

    System.out.printf("The circumference is %d\n",c); //display circumference;
    You are using the wrong formatter in the printf method. %d outputs integer types - not doubles.
    Read up on the printf formatter types.

    Wishes Ada xx
    If to Err is human - then programmers are most human of us all.
    "The Analytical Engine offers a new, a vast, and a powerful language . . .
    for the purposes of mankind
    ."
    Augusta Ada Byron, Lady Lovelace (1851)

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    Default Re: my program for calculating the circumference and area isn't working

    I can't displayed the error message here because the windows command line will not allow me to copy my error message
    See https://www.microsoft.com/resources/....mspx?mfr=true

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    Default Re: my program for calculating the circumference and area isn't working

    Thanks here is the output of my program after entered the radius:


    Enter the radius8.90
    Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Scanner.java:864)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextInt(Scanner.java:2117)
    at java.util.Scanner.nextInt(Scanner.java:2076)
    at circumference.main(circumference.java:22)
    Press any key to continue . . .

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    Default Re: my program for calculating the circumference and area isn't working

    Quote Originally Posted by noblegas View Post
    Thanks here is the output of my program after entered the radius:
    Read the error message. It clearly says "Input Mismatch", so there is something wrong with the way you retrieve input from the user.
    Further down it tells us you use:
    java.util.Scanner.nextInt()
    But in the example you have shown us at the top you have inputted a double. That is clearly not compatible.

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    Default Re: my program for calculating the circumference and area isn't working

    You are using the wrong formatter in the printf method. %d outputs integer types - not doubles.
    Read up on the printf formatter types.
    Thanks Ada, for coming back to life just to help me out with my java program error. What is the printf formatter type for a double?

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    Default Re: my program for calculating the circumference and area isn't working

    What did you find when you Googled 'java formatter'?

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    Default Re: my program for calculating the circumference and area isn't working

    When I google 'java formatter' the 1st website that pops up is oracle . (Formatter (Java Platform SE 7 ))

    the formatter for 'double' is 'e' so I modify my code

    Here is what my code looks like now :

    /circumference.java
    //program that calculates the area and circumference of a circle
     
    import java.util.Scanner; //program uses class scanner
     
    public class circumference{
     
    	//main method begins execution of Java application
     
    	public static void main(String args[]){
     
    	//create scanner to obtain input from the command line
     
    	Scanner input = new Scanner(System.in);
     
    	double a; //declares Area
    	double c; //declares circumferenceFunny How Time Slips Away
     
    	double r; //declares the radius
     
    	System.out.print("Enter the radius"); //prompt
    	r=input.nextdouble(); //read first number the user
     
    	c=2*3.14*r;
     
    	System.out.printf("The circumference is %e\n",c); //display circumference;
     
    }//end method main
     
    }//end class circumference

    the code still won't compile correctly. What did I do wrong?

  13. #13
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    Default Re: my program for calculating the circumference and area isn't working

    What compiler errors are you getting? Always post error messages in their entirety that you want help with.

  14. #14
    Member Ada Lovelace's Avatar
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    Default Re: my program for calculating the circumference and area isn't working

    I am pretty sure the %e would not cause a compiler error as it is a legal
    formatter type. Is that really the one you want to use? What do you
    think the 'e' actually stands for?

    Wishes Ada xx
    If to Err is human - then programmers are most human of us all.
    "The Analytical Engine offers a new, a vast, and a powerful language . . .
    for the purposes of mankind
    ."
    Augusta Ada Byron, Lady Lovelace (1851)

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