separating string into separate variables without arrays

Question

I need help separating a string into separate variables. I am trying to make a program that will get user input using nextLine() then i would need to separate the characters in that string.

For example the user could input the line 23plus or 2 3 plus.

Ive read about .split but that would only work when there are spaces in the input. I could put say that the first number is charAt(0) but how would i get the rest?

How can your program distinguish between `23plus` meaning `23 plus` and `23plus` meaning `2 3 plus`? — gzm0, Apr 01 '13 at 21:47
This doesn't make sense. Given the input `1234plus` what does your logic do? `12 34 plus` `1 234 plus`? — Boris the Spider, Apr 01 '13 at 21:48
You cannot split a line unless you know the general structure of the line and how you're going to split it. You need to tell us these things as well as more examples of possible input and output if we're to help. As written your question doesn't make sense, and isn't answerable. — Hovercraft Full Of Eels, Apr 01 '13 at 21:48
its supposed to be a single digit calculator. i would take one digit and do the operation — Alex Verstivskiy, Apr 01 '13 at 21:49
*"Ive read about .split but that would only work when there are spaces in the input"* That's not even *remotely* true: http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#split(java.lang.String) You might also look at [`Pattern`](http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html), or even just [`String#indexOf`](http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#indexOf(int)) and [`String#substring`](http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#substring(int)). — T.J. Crowder, Apr 01 '13 at 21:49
You could probably just collect the line as a string, remove all of the whitespace and iteratively process each string element in a loop. — Robb, Apr 01 '13 at 21:54

Aubin · Answer 1 · 2013-04-01T22:07:33.757

1

You say, the problem is 'one digit calculator' with postfixed notation 23+ :

digits = digits.replaceAll( "\\\\s","" );
First digit: int op1 = Integer.parseInt( digits.charAt(0));
Second digit: int op2 = Integer.parseInt( digits.charAt(1));
operator : digits.charAt(2), as I suggest to use +, -, /, *, used in a switch/case
result: 5

edited Apr 01 '13 at 22:07

answered Apr 01 '13 at 21:51

Aubin

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"user could input the line 23plus or 2 3 plus" - this doesn't deal with the second case very well... – Boris the Spider Apr 01 '13 at 21:51
how would this work if there are spaces so at index 1 there would be a space? – Alex Verstivskiy Apr 01 '13 at 21:54
http://stackoverflow.com/questions/5455794/removing-whitespace-from-strings-in-java – Robb Apr 01 '13 at 21:55
Purge the spaces with `s.replaceAll("\\s","");` – Aubin Apr 01 '13 at 21:56
@Aubin if you add that to your answer I will remove the down vote as your answer will then answer the question fully. – Boris the Spider Apr 01 '13 at 22:03

Boris the Spider · Answer 2 · 2013-04-01T22:01:32.093

How about looping over the String char by char and checking if it's a digit:

    final List<Integer> values = new LinkedList<>();
    final StringBuilder operator = new StringBuilder();
    for (final char c : input.toCharArray()) {
        if (Character.isDigit(c)) {
            values.add(Integer.parseInt(Character.toString(c)));
        } else if (!Character.isWhitespace(c)) {
            operator.append(c);
        }
    }

Note: This will only work if the input is of the form "WdigitWdigitWoperator" where "W" is optional white space.

But I understand that that is the case from your question.

Another option is to use regex, this would look something like:

    final Pattern p = Pattern.compile("^\\s*+(?<firstDigit>\\d)\\s*+(?<secondDigit>\\d)\\s*+(?<operator>\\w++)$");

    final Matcher matcher = p.matcher(input);
    if(matcher.matches()) {
        System.out.println(matcher.group("firstDigit"));
        System.out.println(matcher.group("secondDigit"));
        System.out.println(matcher.group("operator"));
    }

If this is a homework assignment (which I suspect it is) this may not be an acceptable solution however.

separating string into separate variables without arrays

2 Answers2