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Thread: Simple Nested Do/While Loop

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    Default Simple Nested Do/While Loop

    I was wondering if you can help me out with this code, I am learning on my own mostly from a book.
    The code runs fine but in the 2nd do/while statement I am curious about the condition: (ch=='\n') or (ch=='\r'); Why would ch be equal to a carrage return or line feed? I found out that line feed and carriage returns occur when a keyboard character is input, but do they occur continuously? Why not use the condition: while(ch != 'K'); this condition should run the loop until 'K' is selected on the keyboard, shouldn't it?

    Thanks in advance-Farmer

    public class HSGuess4 {
    public static void main(String[] args) throws java.io.IOException{
    char ch, answer = 'K';

    do{
    System.out.println("I'm thinkning of a letter between A and Z ");
    System.out.println("Can you guess it: ");

    //read a letter, but skip cr/lf (carrage return and line feed)
    do{
    ch = (char) System.in.read(); // get char from keyboard command
    } while(ch == '\n'| ch == '\r');

    if(ch == answer) System.out.println("**Right**");

    else{
    System.out.println("Sorry you're ");
    if(ch < answer) System.out.println("too low");
    else System.out.println("too high");
    System.out.println("Try again!\n");
    }
    } while(answer !=ch);
    }
    }


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    Default Re: Simple Nested Do/While Loop

    The first time through, there shouldn't be any cr/lf characters, but after each incorrect answer, it retries by going round the loop again, so the cr/lf from the previous entry is still waiting to be read.

    This is one disadvantage of using a 'raw' input stream. Normally one would wrap System.in in a Scanner or some other convenient higher-level input class.

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    Default Re: Simple Nested Do/While Loop

    dlorde,

    Thanks for you input. I have seen the Scanner class used but have not tried it yet. I am just working my way through text book examples. Again your feedback was helpful, thank you.

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