regex for validating input C 200 50 - regex

Question

How do i write regex for below?
C 200 50
C/c can be upper case or lower case.
200 - 0 to 200 range
50 - o to 50 range
All three words are separated by space and there can be 1 or more space.
This is what i tried so far.
public static void main(String[] args) {
String input = "C 200 50";
String regex = "C{1} ([01]?[0-9]?[0-9]|2[0-9][0]|20[0]) ([01]?[0-5]|[0-5][0])";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(input);
boolean found = false;
while (matcher.find()) {
System.out.println("I found the text "+matcher.group()+" starting at index "+
matcher.start()+" and ending at index "+matcher.end());
found = true;
}
}
Not sure how to have multiple space, upper or lower first 'C'

Answer 1

If you are validating a string, you must be expecting a whole string match. It means you should use .matches() rather than .find() method as .matches() requires a full string match.
To make c match both c and C you may use Pattern.CASE_INSENSITIVE flag with Pattern.compile, or prepend the pattern with (?i) embedded flag option.
To match one or more spaces, one would use + or \\s+.
To match leading zeros, you may prepend the number matching parts with 0*.
Hence, you may use
String regex = "(?i)C\\s+0*(\\d{1,2}|1\\d{2}|200)\\s+0*([1-4]?\\d|50)";
and then
See the regex demo and a Regulex graph:
See the Java demo:
String input = "C 200 50";
String regex = "(?i)C +0*(\\d{1,2}|1\\d{2}|200) +0*([1-4]?\\d|50)";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(input);
boolean found = false;
if (matcher.matches()) {
System.out.println("I found the text "+matcher.group()+" starting at index "+
matcher.start()+" and ending at index "+matcher.end());
found = true;
}
Output:
I found the text C 200 50 starting at index 0 and ending at index 8
If you need a partial match, use the pattern with .find() method in a while block. To match whole words, wrap the pattern with \\b:
String regex = "(?i)\\bC\\s+0*(\\d{1,2}|1\\d{2}|200)\\s+0*([1-4]?\\d|50)\\b";