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Thread: Looping questions

  1. #1
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    Default Looping questions

    I am trying to build up the alphabet character by character. Like:
    a
    ab
    abc
    abcd

    Well as of now I can only print out the alphabet with my loop like abcdefg...z. Can anyone help me out?

    So here is the code I am trying to use:
    public void loop4()
        {
            char alph = 'a';
                while(alph <= 'z')
                {
     
                    System.out.println(alph);
                    alph++;
     
                }
        }


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    Default Re: Looping questions

    What is the logic for the printout?
    Is it something like this:
    print 1 char on first line
    print 2 chars on second line
    print 3 chars on third line
    etc
    print 26 chars on the 26th line

    Do you see the pattern there?
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Looping questions

    It's either you make a nested loop for printing array from a-next.

    Or you make a string variable and concatenate the the characters in that string and print it, that way you're not going to need the nested loop

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    Default Re: Looping questions

    Still confused... how can a nested loop help? The trouble I am having is that everytime I loop through once, I loose the previous letter. What would the loop within this loop be doing? Or do I need my current loop inside another loop?

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    Default Re: Looping questions

    You should consider the StringBuilder class to help with this exercise.

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    Default Re: Looping questions

    Using a StringBuilder to concatenate characters together is probably the easier way. The basic idea is as you loop through from 'a' to 'z', you concatenate/append the next letter in the alphabet to the StringBuilder, and then print out the StringBuilder.

    Here's something to help you get started using bits of what you already have:

    char alph = 'a';
    StringBuilder strBuilder = new StringBuilder(); // <= Initialise the StringBuilder here
     
    while (alph <= 'z') {
        // Write code to append alph to the StringBuilder
        // Write code to print out the contents of the StringBuilder
     
        alph++;
    }

    See StringBuilder (Java Platform SE 7 ) for the API documentation for StringBuilder to find out the code you need to write above.

    The nested-loop method can be a bit mind-bending for the novice. The basic idea is to use 2 variables to keep track of the iterations in each of the loops, with the inner loop's iterations dependent on the progress of the outer loop. The following is an example using nested 'while' loops:

    char outerAlph = 'a';
    while (outerAlph <= 'z') {
        char innerAlph = 'a';
        while (innerAlph <= outerAlph) {
            // Write code here
     
            innerAlph++;
        }
        // Write code here
     
        outerAlph++;
    }

  7. The Following User Says Thank You to jashburn For This Useful Post:

    vysero (March 10th, 2014)

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    Default Re: Looping questions

    I understand now thank you!

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