In this blog, we will create a program to find the difference between two dates in C++ programming language.
What is Date difference?
The difference of two dates in years, months, and days is quite simple. All we need to do is subtract the day, month, and year of the start date from the day, month, and year of the end date.
Algorithm for the respective code
Leap year: is a year that comes every 4 years. Generally, a year consists of 365 days, but a leap year has 366 days. The next day is scheduled for February 29.
(*Note: Centennial years are not leap years unless they are divisible by 400).
E.g. 1600 is a century year and also a leap year. Because it is divisible by 400. On the other hand, 1700 is a century year, not a leap year. Because it’s not divisible by 400.
Things we should know:
- The year “0” does not exist.
- February 29 only exists in a leap year.
C++ code for the respective program
#include <iostream>
using namespace std;
int check_leap_year(int year)
{
if( year%4==0 && year%100!=0 || year%400==0 ) //if year is a leap year
return 1;
else
return 0;
}
int no_of_days_in_month(int month, int year)
{
// jan, march, may, july, aug, oct, dec contains 31 days
if( month==1 || month==3 || month==5 || month==7 || month==8 || month==10 || month==12 )
return 31;
// april, jun, sept, nov contains 30 days
if( month==4 || month==6 || month==9 || month==11 )
return 30;
if( month==2 )
{
int n=check_leap_year(year);
if(n==1) // if year is a leap year then Feb will contain 29 days, otherwise it contains 28 days
return 29;
else
return 28;
}
}
long long int difference_of_days(int day1,int month1, int year1, int day2, int month2, int year2)
{
if(year1==year2)
{
if(month1==month2)
{
if(day1==day2) //for same dates
return 0;
else
return abs(day1-day2); //for same year, same month but diff days
}
else if(month1<month2)
{
int result=0;
for(int i=month1; i<month2; i++)
result=result+no_of_days_in_month(i,year1);
if(day1==day2) //for same year, same day but diff month
return result;
else if(day1<day2)
{
result=result+(day2-day1);
return result;
}
else
{
result=result-(day1-day2);
return result;
}
}
else
{
int result=0;
for(int i=month2; i<month1; i++)
result=result+no_of_days_in_month(i,year1);
if(day1==day2)
return result;
else if(day2<day1)
{
result=result+(day1-day2);
return result;
}
else
{
result=result-(day2-day1);
return result;
}
}
}
else if(year1<year2)
{
int temp=0;
for(int i=year1; i<year2; i++)
{
if(check_leap_year(i))
temp=temp+366;
else
temp=temp+365;
}
if(month1==month2)
{
if(day1==day2) //for same month, same day but diff year
return temp;
else if(day1<day2)
return temp+(day2-day1);
else
return temp-(day1-day2);
}
else if(month1<month2)
{
int result=0;
for(int i=month1; i<month2; i++)
result=result+no_of_days_in_month(i,year2);
if(day1==day2) // for same day, diff year and diff month
return temp+result;
else if(day1<day2)
{
result=result+(day2-day1);
return temp+result;
}
else
{
result=result-(day1-day2);
return temp+result;
}
}
else
{
int result=0;
for(int i=month2; i<month1; i++)
result=result+no_of_days_in_month(i,year2);
if(day1==day2)
return temp-result;
else if(day2<day1)
{
result=result+(day1-day2);
return temp-result;
}
else
{
result=result-(day2-day1);
return temp-result;
}
}
}
else
{
int temp=0;
for(int i=year2; i<year1; i++)
{
if(check_leap_year(i))
temp=temp+366;
else
temp=temp+365;
}
if(month1==month2)
{
if(day1==day2) // for same day, same month but diff year
return temp;
else if(day2<day1)
return temp+(day1-day2);
else
return temp-(day2-day1);
}
else if(month2<month1)
{
int result=0;
for(int i=month2; i<month1; i++)
result=result+no_of_days_in_month(i,year1);
if(day1==day2)
return temp+result;
else if(day2<day1)
{
result=result+(day1-day2);
return temp+result;
}
else
{
result=result-(day2-day1);
return temp+result;
}
}
else
{
int result=0;
for(int i=month1; i<month2; i++)
result=result+no_of_days_in_month(i,year1);
if(day1==day2) // for same day, diff year and diff month
return temp-result;
else if(day1<day2)
{
result=result+(day2-day1);
return temp-result;
}
else
{
result=result-(day1-day2);
return temp-result;
}
}
}
}
int main()
{
int day1,day2,month1,month2,year1,year2;
int n;
// Inputting both dates
cout<<"Enter the first date=>\n";
cout<<"Day :";
cin>>day1;
cout<<"Month (ex: for january write '1') :";
cin>>month1;
cout<<"Year :";
cin>>year1;
n=no_of_days_in_month(month1,year1);
// checking if entered date is valid or not
if(day1<1 || day1>n || month1<1 || month1 >12 || year1 <1)
{
cout<<"\nEntered date is not valid";
exit(0); // exiting from the program if the entered date is invalid
}
cout<<"\nEnter the second date=>\n";
cout<<"Day :";
cin>>day2;
cout<<"Month (ex: for january write '1') :";
cin>>month2;
cout<<"Year :";
cin>>year2;
n=no_of_days_in_month(month2,year2);
if(day2<1 || day2>n || month2<1 || month2 >12 || year2 <1)
{
cout<<"\nEntered date is not valid";
exit(0);
}
// Counting the difference between 2 dates in terms of no of days
long long int diff = difference_of_days(day1, month1, year1, day2, month2, year2);
cout<<"\nDifference between 2 dates in terms of =>";
cout<<"\nNo. of days :"<<diff<<" days";
cout<<"\nNo. of hours :"<<diff*24<<" hours";
return 0;
}
Output of the above code
