Finding the number of different dates in a string

Question

I am stuck in a question. A paragraph which contained some dates in format DD-MM-YYYY, find number of distinct years in the paragraph .Can this be solved using regex?

Pure regex alone can't do this, but regex could be used to isolate and extract the dates. What programming language or tool are you using? — Tim Biegeleisen, Apr 01 '18 at 10:55
Also, please post some sample inputs and outputs for the same. — Robo Mop, Apr 01 '18 at 11:08
I am using JAVA. Some random words with date 12-01-1990 and some more words with date 12-12-2017 and again some random words with same date 12-05-1990. Expected Output: 3 Since it contains 3 dates — Siddharth Poonia, Apr 01 '18 at 13:01
read this: https://stackoverflow.com/questions/432493/how-do-you-access-the-matched-groups-in-a-javascript-regular-expression — guillaume girod-vitouchkina, Apr 01 '18 at 14:44

score 0 · Answer 1 · answered Apr 01 '18 at 14:52

Regex for date var regex = /(?:(?:[0-2][0-9]|[3][01])-(?:[0][13578]|[1][02])|(?:[0-2][0-9]|30)-(?:[0][469]|11)|(?:[0-2][0-9])-02)-[0-9]{4}/g;.

The above regex cannot match leap years.

To find the count of dates in the pargraph in JS is

function dateCount(input){
    const regex = /(?:(?:[0-2][0-9]|[3][01])-(?:[0][13578]|[1][02])|(?:[0-2][0-9]|30)-(?:[0][469]|11)|(?:[0-2][0-9])-02)-[0-9]{4}/g;
    let m;
    var noDates= 0; 
    while ((match = regex.exec(input)) !== null) {
        dateCounter++; 
//This is to prevent from running into infinite loop
        if (match.index === regex.lastIndex) {
            regex.lastIndex++;
        }
    }
    console.log(dateCounter);
}

Finding the number of different dates in a string

1 Answers1