Finding number of days between two dates using StringStream

Given two strings str1 and str2 which represent two dates, the task is to count the number of days between given two dates. Given that dates given are beyond 1971. Examples:

Input: str1 = “2020-01-29”, str2 = “2020-01-30” Output: 1 Explanation: The number of days between 29^th January and 30^th January is 1. Input: str1 = “1971-06-29”, str2 = “2019-06-23” Output: 17526

Approach: The idea is to convert both the dates into its respective seconds. Since there are 86, 400 seconds in a day, the number of days between both the days can be found out by dividing the difference of seconds with 86, 400. Below is the implementation of the above approach: 

CPP

// C++ implementation of the above approach
#include <iostream>
#include <sstream>
#include <string>
using namespace std;

// Function to find the number of days
// between given two dates
int daysBetweenDates(string date1, string date2)
{
    stringstream ss(date1 + "-" + date2);
    int year, month, day;
    char hyphen;

    // Parse the first date into seconds
    ss >> year >> hyphen >> month >> hyphen >> day;
    struct tm starttm = { 0, 0, 0, day,
                        month - 1, year - 1900 };
    time_t start = mktime(&starttm);

    // Parse the second date into seconds
    ss >> hyphen >> year >> hyphen
        >> month >> hyphen >> day;
    struct tm endtm = { 0, 0, 0, day,
                        month - 1, year - 1900 };
    time_t end = mktime(&endtm);

    // Find out the difference and divide it
    // by 86400 to get the number of days
    return abs(end - start) / 86400;
}

// Driver code
int main()
{
    string str1 = "2019-09-12";
    string str2 = "2020-08-04";
    cout << daysBetweenDates(str1, str2);
    return 0;
}

Java

// Java implementation of the above approach
import java.util.*;
import java.time.*;
import java.time.format.*;
import java.time.temporal.*;

class GFG {

  // Function to find the number of days
  // between given two dates
  static long daysBetweenDates(String date1, String date2)
  {
    DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy MM dd");

    String[] ss = (String.valueOf(date1) + "-"
                   + String.valueOf(date2))
      .split("-");

    String year, month, day;
    year = ss[0];
    month = ss[1];
    day = ss[2];

    LocalDate start = LocalDate.parse(year + " " + month + " " + day , dtf);

    year = ss[3];
    month = ss[4];
    day = ss[5];
    LocalDate end =LocalDate.parse(year + " " + month + " " + day, dtf);

    return ChronoUnit.DAYS.between(start, end);
  }

  // Driver code
  public static void main(String[] args)
  {
    String str1 = "2019-09-12";
    String str2 = "2020-08-04";
    System.out.println(daysBetweenDates(str1, str2));
  }
}

// This code is contributed by phasing17

Python3

# Python3 implementation of the above approach
import time, datetime, math

# Function to find the number of days
# between given two dates
def daysBetweenDates( date1,  date2):

    ss = [int(i) for i in (date1 + "-" + date2).split("-")]

    # Parse the first date into seconds
    year = ss[0]
    month = ss[1]
    day = ss[2];
    start = datetime.datetime(year, month, day);

    # Parse the second date into seconds
    year = ss[3]
    month = ss[4]
    day = ss[5];
    end = datetime.datetime(year, month, day);
    end = time.mktime(end.timetuple())
    start = time.mktime(start.timetuple())
    diff = (start - end)

    # Find out the difference and divide it
    # by 86400 to get the number of days
    return  math.ceil(abs(diff) / 86400)

# Driver code
str1 = "2019-09-12";
str2 = "2020-08-04";
print(daysBetweenDates(str1, str2));

# This code is contributed by phasing17

C#

// C# implementation of the above approach
using System;
using System.Collections.Generic;

class GFG
{

  // Function to find the number of days
  // between given two dates
  static int daysBetweenDates(string date1, string date2)
  {
    string[] ss = (Convert.ToString(date1) + "-"
                   + Convert.ToString(date2))
      .Split('-');

    int[] ss1 = new int[ss.Length];

    for (int i = 0; i < ss.Length; i++)
      ss1[i] = Convert.ToInt32(ss[i]);


    // Parse the first date into seconds
    var start = new DateTime(ss1[0], ss1[1], ss1[2]);

    // Parse the second date into seconds
    var end = new DateTime(ss1[3], ss1[4], ss1[5]);

    // Find out the difference and divide it
    // by 86400 to get the number of days
    return (end - start).Days;
  }

  // Driver code
  public static void Main(string[] args)
  {
    string str1 = "2019-09-12";
    string str2 = "2020-08-04";
    Console.WriteLine(daysBetweenDates(str1, str2));
  }
}


// This code is contributed by phasing17

Javascript

// JS implementation of the above approach

// Function to find the number of days
// between given two dates
function daysBetweenDates( date1,  date2)
{
    let ss = (date1 + "-" + date2).split("-").map(function (a) {return parseInt(a)});
    let year, month, day;
    let hyphen;

    // Parse the first date into seconds
    year = ss[0]
     month = ss[1]
     day = ss[2];
    let start = new Date(year, month, day);

    // Parse the second date into seconds
        year = ss[3]
     month = ss[4]
     day = ss[5];
    let end = new Date(year, month, day - 1);

    // Find out the difference and divide it
    // by (1000 * 60 * 60 * 24) to get the number of days
    return  Math.floor(Math.abs(end - start) / (1000 * 60 * 60 * 24) );
}

// Driver code
let str1 = "2019-09-12";
let str2 = "2020-08-04";
console.log(daysBetweenDates(str1, str2));

// This code is contributed by phasing17

Output:

327

Time Complexity: O(1)
Auxiliary Space: O(1), As constant extra space is used.