Thread: 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++;
 
            }
    }

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

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?

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

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++;
}

I understand now thank you!