Extracting all present dates in any given String using Regular Expressions
Last Updated : 23 Mar, 2023
Given a string Str, the task is to extract all the present dates from the string. Dates can be in the format i.e., mentioned below:
- DD-MM-YYYY
- YYYY-MM-DD
- DD Month YYYY
Examples:
Input: Str = "The First Version was released on 12-07-2008.The next Release will come on 12 July 2009. The due date for payment is 2023-09-1. India gained its freedom on 15 August 1947 which was a Friday. Republic Day is a public holiday in India where the country marks and celebrates the date on which the Constitution of India came into effect on 26-1-1950."
Output: 12-07-2008
12 July 2009
2023-09-1
15 August 1947
26-1-1950
Approach: The problem can be solved based on the following idea:
Create a regex pattern to validate the number as written below:
regex = "\\d{2} - \\d{2} - \\d{4}",
"[0 - 9]{2}[/]{1}[0 - 9]{2}[/]{1}[0 - 9]{4}",
"\\d{1, 2} - (January|February|March|April|May|June|July|August|September|October|November|December)-\\d{4}",
"\\d{4} - \\d{1, 2} - \\d{1, 2}",
"[0 - 9]{1, 2}\\s(January|February|March|April|May|June|July|August|September|October|November|December)\\s\\d{4}",
"\\d{1, 2} - \\d{1, 2} - \\d{4}"
Where,
- [d]{2}: This pattern will match two of the preceding items if they are Digits or not.
- |: Either of them should be there
Follow the below steps to implement the idea:
- Create a regex expression to extract all the present dates from the string.
- Use Pattern class to compile the regex formed.
- Use the matcher function to find.
- If it is valid, return true. Otherwise, return false.
Below is the code implementation of the above-discussed approach:
C++ // C++ code for the above approach #include <iostream> #include <regex> using namespace std; // Driver Code int main() { // String containing in it string str = "The First Version was released on 12-07-2008." "Next Release will might come on 12 July 2009. " "The due date for payment is 2023-09-1." "India gained its freedom on 15 August 1947 which was a Friday." "Republic Day is a public holiday in India where the country marks and celebrates " "the date on which the Constitution of India came into effect on 26-1-1950."; // You can Add n number of date // formats in the below given // String Array. string strPattern[] = { "\\d{2}-\\d{2}-\\d{4}", "[0-9]{2}/{1}[0-9]{2}/{1}[0-9]{4}", "\\d{1,2}-(January|February|March|April|May|June|July|August|September|October|November|December)-\\d{4}", "\\d{4}-\\d{1,2}-\\d{1,2}", "[0-9]{1,2}\\s(January|February|March|April|May|June|July|August|September|October|November|December)\\s\\d{4}", "\\d{1,2}-\\d{1,2}-\\d{4}" }; for (int i = 0; i < 6; i++) { regex pattern(strPattern[i]); sregex_iterator matcher(str.begin(), str.end(), pattern); sregex_iterator end; while (matcher != end) { cout << matcher->str() << endl; matcher++; } } return 0; } // This Code is Contributed by Prasad Kandekar(prasad264) // Java code for the above approach import java.io.*; import java.util.regex.Matcher; import java.util.regex.Pattern; public class GFG { // Driver Code public static void main(String[] args) { // String containing in it String str = "The First Version was released on 12-07-2008." + "Next Release will might come on 12 July 2009. " + "The due date for payment is 2023-09-1." + "India gained its freedom on 15 August 1947 which was a Friday." + "Republic Day is a public holiday in India where the country marks and celebrates " + "the date on which the Constitution of India came into effect on 26-1-1950."; // You can Add n number of date // formats in the below given // String Array. String strPattern[] = { "\\d{2}-\\d{2}-\\d{4}", "[0-9]{2}[/]{1}[0-9]{2}[/]{1}[0-9]{4}", "\\d{1, 2}-(January|February|March|April|May|June|July|August|September|October|November|December)-\\d{4}", "\\d{4}-\\d{1, 2}-\\d{1, 2}", "[0-9]{1, 2}\\s(January|February|March|April|May|June|July|August|September|October|November|December)\\s\\d{4}", "\\d{1, 2}-\\d{1, 2}-\\d{4}" }; for (int i = 0; i < strPattern.length; i++) { Pattern pattern = Pattern.compile(strPattern[i]); Matcher matcher = pattern.matcher(str); while (matcher.find()) { System.out.println(matcher.group()); } } } } # python code for the above approach import re # String containing in it str = "The First Version was released on 12-07-2008." \ "Next Release will might come on 12 July 2009. " \ "The due date for payment is 2023-09-1." \ "India gained its freedom on 15 August 1947 which was a Friday." \ "Republic Day is a public holiday in India where the country marks and celebrates " \ "the date on which the Constitution of India came into effect on 26-1-1950." # You can Add n number of date formats in the below given String Array. str_pattern = [ "\\d{2}-\\d{2}-\\d{4}", "[0-9]{2}/{1}[0-9]{2}/{1}[0-9]{4}", "\\d{1,2}-(January|February|March|April|May|June|July|August|September|October|November|December)-\\d{4}", "\\d{4}-\\d{1,2}-\\d{1,2}", "[0-9]{1,2}\\s(January|February|March|April|May|June|July|August|September|October|November|December)\\s\\d{4}", "\\d{1,2}-\\d{1,2}-\\d{4}" ] for pattern in str_pattern: for match in re.finditer(pattern, str): print(match.group()) # This Code is Contributed by Prasad Kandekar(prasad264) // C# code for the above approach using System; using System.Text.RegularExpressions; class GFG { static void Main(string[] args) { // String containing in it string str = "The First Version was released on 12-07-2008." + "Next Release will might come on 12 July 2009. " + "The due date for payment is 2023-09-1." + "India gained its freedom on 15 August 1947 which was a Friday." + "Republic Day is a public holiday in India where the country marks and celebrates " + "the date on which the Constitution of India came into effect on 26-1-1950."; // You can Add n number of date // formats in the below given // String Array. string[] strPattern = new string[] { "\\d{2}-\\d{2}-\\d{4}", "[0-9]{2}[/]{1}[0-9]{2}[/]{1}[0-9]{4}", "\\d{1, 2}-(January|February|March|April|May|June|July|August|September|October|November|December)-\\d{4}", "\\d{4}-\\d{1, 2}-\\d{1, 2}", "[0-9]{1, 2}\\s(January|February|March|April|May|June|July|August|September|October|November|December)\\s\\d{4}", "\\d{1, 2}-\\d{1, 2}-\\d{4}" }; foreach (string pattern in strPattern) { MatchCollection matches = Regex.Matches(str, pattern); foreach (Match match in matches) { Console.WriteLine(match.Value); } } } } // JavaScript code for the above approach // String containing in it const str = "The First Version was released on 12-07-2008." + "Next Release will might come on 12 July 2009. " + "The due date for payment is 2023-09-1." + "India gained its freedom on 15 August 1947 which was a Friday." + "Republic Day is a public holiday in India where the country marks and celebrates " + "the date on which the Constitution of India came into effect on 26-1-1950."; // You can Add n number of date // formats in the below given // String Array. const strPattern = [ "\\d{2}-\\d{2}-\\d{4}", "[0-9]{2}/{1}[0-9]{2}/{1}[0-9]{4}", "\\d{1,2}-(January|February|March|April|May|June|July|August|September|October|November|December)-\\d{4}", "\\d{4}-\\d{1,2}-\\d{1,2}", "[0-9]{1,2}\\s(January|February|March|April|May|June|July|August|September|October|November|December)\\s\\d{4}", "\\d{1,2}-\\d{1,2}-\\d{4}" ]; for (let i = 0; i < 6; i++) { const pattern = new RegExp(strPattern[i], 'g'); let matcher = str.matchAll(pattern); for (const match of matcher) { console.log(match[0]); } } // This code is contributed by Prajwal Kandekar Output12-07-2008 2023-09-1 12 July 2009 15 August 1947 12-07-2008 26-1-1950
Time Complexity: O(n*m), N is the length of the input string and M is the number of date formats in the strPattern array.
Space Complexity: O(k), where k is the total number of matched dates.
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