Getting a double out of a string

Question

i have a string containing the following: \"Did It Your Way, 11.95 The History of Scotland, 14.50, Learn Calculus in One Day, 29.95\" is there any way to get the doubles fro

Answer 1

Use Regular Expressions (regex[p]) module of your favourite language, construct a Matcher for the pattern \d+\.\d+, apply the matcher for the input string and you get the matching substrings as capture groups.

Answer 2

This finds doubles, whole numbers (with and without a decimal point), and fractions (a leading decimal point):

public static void main(String[] args)
{
    String str = "This is whole 5, and that is double 11.95, now a fraction .25 and finally another whole 3. with a trailing dot!";
    Matcher m = Pattern.compile("(?!=\\d\\.\\d\\.)([\\d.]+)").matcher(str);
    while (m.find())
    {
        double d = Double.parseDouble(m.group(1));
        System.out.println(d);
    }
}

Output:

5.0
11.95
0.25
3.0

Answer 3

Use scanner (example from TutorialPoint). Regex expressions suggested above fail on this example: "Hi! -4 + 3.0 = -1.0 true" detects {3.0, 1,0}.

   String s = ""Hello World! -4 + 3.0 = -1.0 true"";

   // create a new scanner with the specified String Object
   Scanner scanner = new Scanner(s);

   // use US locale to be able to identify doubles in the string
   scanner.useLocale(Locale.US);

   // find the next double token and print it
   // loop for the whole scanner
   while (scanner.hasNext()) {

   // if the next is a double, print found and the double
   if (scanner.hasNextDouble()) {
   System.out.println("Found :" + scanner.nextDouble());
   }

   // if a double is not found, print "Not Found" and the token
   System.out.println("Not Found :" + scanner.next());
   }

   // close the scanner
   scanner.close();
   }

Answer 4

String text = "Did It Your Way, 11.95 The History of Scotland, 14.50, Learn Calculus in One Day, 29.95";

List<Double> foundDoubles = Lists.newLinkedList();

String regularExpressionForDouble = "((\\d)+(\\.(\\d)+)?)";
Matcher matcher = Pattern.compile(regularExpressionForDouble).matcher(text);
while (matcher.find()) {
    String doubleAsString = matcher.group();
    Double foundDouble = Double.valueOf(doubleAsString);
    foundDoubles.add(foundDouble);
}

System.out.println(foundDoubles);

Answer 5

Here is how I did it when I was getting input from a user and didn't know what it would look like:

    Vector<Double> foundDoubles = new Vector<Double>();

    Scanner reader = new Scanner(System.in);
    System.out.println("Ask for input: ");

    for(int i = 0; i < accounts.size(); i++){
        foundDoubles.add(reader.nextDouble());
    }

Answer 6

If you're interested in any and all numbers with digits, a single period, and more digits, you want to use regular expressions. Such as \s\d*.\d\s, indicating a space, followed by digits, a period, more digits, and finished off with a space.