Date manipulation question

Question

Using either cstring or string classes how do I manipulate a date?

I would be getting the date in the format of 11/12/2009 with cin.getline

and I want it to cout November 12, 2009.

Any idea to get me started would be appreciated.

Answer 1

To get you started, you can use as "template" class Date from this tutorial: http://www.learncpp.com/cpp-tutorial/89-class-code-and-header-files/

And these links for date format manipulation:

http://stackoverflow.com/questions/3263661/format-a-date-in-c, 

http://stackoverflow.com/questions/7753145/customize-date-format-in-c and 

http://stackoverflow.com/questions/7135842/converting-date-class-to-string

Answer 2

First thing why not simply use time_t or SYSTEMTIME etc to get the time .

 time_t rawtime;
 time ( &rawtime );

or

 SYSTEMTIME st, lt;    
    GetSystemTime(&st);
    GetLocalTime(&lt);  

and then calculate the difference between time and store it in string or do watever you want.

Thanks

---

Rupesh Shukla

Answer 3

Here's an example of a routine I wrote to parse a date format we use.  You'd have to adjust it, of course, to fit your date format.  I pass a CString into this routine.

//
// Converts an XML Timestamp to a CTime object
// Timestamp format = CCYY-MM-DD HH:MM:SS
//
CTime FromTimeStamp(LPCTSTR cTimeStamp)
{
	CTime cTime = CTime::GetCurrentTime();
	if(!(cTimeStamp == NULL || _tcslen(cTimeStamp) == 0)) {
		int month, day, year, hours , minutes, seconds; 
		_stscanf_s(cTimeStamp,_T("%d-%d-%d %d:%d:%d"),&year, &month, &day, &hours, &minutes, &seconds); 
		if(year == 1969) { // Epoch for CTime is 12/31/1969, but this doesn't work on all implemntations
				// of Windows so let's force it to the first date that always works.  If the 
				// file reads that old then what's a few days for the sake of saving an assert.
			year = 1970;
			month = 1;
			day = 3;
		}
		if(year < 1970) {
			if(year < 70 && year > 38)
				year += 2000;
			else if(year > 70 && year < 1900)
				year += 1900;
			else
				year = cTime.GetYear();
		}
		// Fix for GMT of 0 where MSFT timezone check subtracts 3600 seconds.  This will 
		// keep the CTime function from claiming an invalid parameter.  Bug is actually
		// in mktime()
		if(year == 1970 && month == 1 && day == 1)
			day = 3;
		cTime = CTime(year, month, day, hours, minutes, seconds); 
	}
	return cTime;
}

Tom

Answer 4

You can use basic time functions:t ime, _time32, _time64 and  asctime_s

described in the link:http://msdn.microsoft.com/en-us/library/1f4c8f33(v=vs.80).aspx and http://msdn.microsoft.com/fr-fr/library/b6htak9c(v=vs.80).aspx

---

Delphine GARRO

Answer 5

I was thinking.

since the date would be manually entered by the user, using cin.getline.  Once entered I would then I would store it in an Array.

I was going to make a function full of "if" statements calling the first two elements in the array and if they == 12 etc.

it would cout " December" . Not sure how to integrate the day and year.

Answer 6

you can use strptime function for this.

Thans

---

Rupesh Shukla

Answer 7

Here is the code I have and it works. I would like to put the "If" statements in their own function and call it in the main. Have been unsuccessful thus far.

# include <string>
#include <iostream>
using namespace std;
int main()
{
string date;
string Month;
string Day;
string Year;
  cout << ("Please enter a date (format: mm/dd/yyyy): ");
  cin >> date;
   
  Month = date.substr(0,2);
  Day = date.substr(3,2);
  Year = date.substr(6,4);
    if (Month == "01")
    {
      cout << "January " << Day << ","<< Year<<endl;          
    }
    else if(Month == "02")
    {
      cout << "February "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "03")
    {
      cout << "March "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "04")
    {
      cout << "April "<< Day << " "<< Year<<endl;           
    }
    else if(Month == "05")
    {
      cout << "May "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "06")
    {
      cout << "June "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "07")
    {
      cout << "July "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "08")
    {
      cout << "August "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "09")
    {
      cout << "September "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "10")
    {
      cout << "October "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "11")
    {
      cout << "November "<< Day << ", "<<Year<<endl;           
    }
    else if(Month == "12")
    {
      cout << "December "<< Day << ", "<< Year<<endl;           
    }
    else
    {
		cout << "Idiot you enter the date incorrectly "<<endl;
	}
        
    
}

Answer 8

>I would like to put the "If" statements in their own
>function and call it in the main. Have been unsuccessful
>thus far.

That should be very simple. What seems to be the problem
you're having? Show the code you've tried.

- Wayne

Answer 9

std::regex: http://www.johndcook.com/cpp_regex.html#replace

Answer 10

Wayne

This is what I attempted to do. It will compile but any date prints the else statement.

# include <string>
#include <iostream>
using namespace std;
void GetMonth(string & );
void GetDay(string &);
void GetYear(string &);
int main()
{
string date;
string Month;
string Day;
string Year;
  cout << ("Please enter a date (format: mm/dd/yyyy): ");
  cin >> date;
   
  GetMonth(date);
  GetDay(date);
  GetYear(date);
    if (Month == "01")
    {
      cout << "January " << Day << ","<< Year<<endl;          
    }
    else if(Month == "02")
    {
      cout << "February "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "03")
    {
      cout << "March "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "04")
    {
      cout << "April "<< Day << " "<< Year<<endl;           
    }
    else if(Month == "05")
    {
      cout << "May "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "06")
    {
      cout << "June "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "07")
    {
      cout << "July "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "08")
    {
      cout << "August "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "09")
    {
      cout << "September "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "10")
    {
      cout << "October "<< Day << ", "<< Year<<endl;           
    }
    else if(Month == "11")
    {
      cout << "November "<< Day << ", "<<Year<<endl;           
    }
    else if(Month == "12")
    {
      cout << "December "<< Day << ", "<< Year<<endl;           
    }
    else
    {
		cout << "Idiot you enter the date incorrectly "<<endl;
	}
        
    return 0;
}
void GetMonth(string &date)
{ 
	string Month;
	
  Month =  date.substr(0,2);
  
	
}
void GetDay(string &date)
{
	string Day;
	
    Day = date.substr(3,2);
}
void GetYear(string &date )
{
	string Year;
	
    Year = date.substr(6,4);
}

Answer 11

void GetMonth(string &date)
{
  string Month;

  Month =  date.substr(0,2);
  
}

Ok, so you computed the value of Month. But you don't do anything with it. Remember, this is a variable that is local to the function only. Did you intend to return the value to the caller, perhaps?

Answer 12

Apparently I misunderstood the assignment. The original code worked but not the way the assignment wanted.

I have to make an array and fill it with months ie "January", "Febuary", etc.  and use the numeric representation of the month as the index. Then I need to convert the numerical string to a int (probably using atoi). 

Then  read in the data in main in the form of mm/dd/YYYY and pass it to a function that determines the month and returns a 

new string with the month as a word…..

Not sure exactly how to due this.

Answer 13

I have to make an array and fill it with months ie "January", "Febuary", etc.  and use the numeric representation of the month as the index. Then I need to convert the numerical string to a int (probably using atoi). 

Then  read in the data in main in the form of mm/dd/YYYY and pass it to a function that determines the month and returns a 

new string with the month as a word…..

Not sure exactly how to due this.

Do you ever pay attention to what others try to suggest to you? Two days ago i gave you a link from where you could borrow the fast and effective (though, rather expensive) way to translate date from string (such as "30/01/2012") into int format using std::istringstream - http://stackoverflow.com/questions/3263661/format-a-date-in-c.

Answer 14

Thanks for the reply Sergey

I did read your earlier post. However we are not at that point in class so I can't use some of that code.  I  know most of the code I need to use I am not sure of how to actually impliment it or how I pass the mm/dd/yyyy to the function  or whether I do the conversion in the main and how I return the new string as month being a word. 

Answer 15

>we are not at that point in class so I can't use some
>of that code.

This is *one* of the problems with asking for help with
course assignments in a public forum. We have no way of
knowing what has or hasn't been covered in the course.

Even if we did, it's *your* assignment so you need to do it
yourself. If the teacher wanted a collaborative or group
effort then everyone in the course could sit down together
and create a single program to be submitted by every student.
While that might make the teacher's job easier - having only
one program to grade - it would not be a very good way to
teach students how to program by themselves.

>I know most of the code I need to use I am not sure of how to
>actually impliment it

Then start coding - you'll learn from your mistakes what
will or won't work. As you refine your approach the task
should become clearer.

>or how I pass the mm/dd/yyyy to the function  

Any way you want. You obviously already know how to pass a
std::string to a function, since you did it in your earlier
code.

>or whether I do the conversion in the main

That's a design decision which you as the programmer must
make yourself.

>and how I return the new string as month being a word.

You should already know how to return a value from a
function. You also should already know how to pass more
than one argument to a function, including pointers and
references.

Break the program down into discrete parts which can be
coded as more or less independent sub-tasks. Then focus
on coding one part of the program (a sub-task) and getting
it to work. Eventually you will have all of the separate
tasks coded and you can then cobble them together to get
the final complete program. Think modularly rather than
trying to construct the entire program in your mind
before writing any code.

- Wayne

Answer 16

Thanks for the reply Sergey

I did read your earlier post. However we are not at that point in class so I can't use some of that code.  I  know most of the code I need to use I am not sure of how to actually impliment it or how I pass the mm/dd/yyyy to the function  or whether I do the conversion in the main and how I return the new string as month being a word. 

I am sorry, but we can not do your work for you. We can only help you in times you get stuck with code. By the way, you also could mention what language features you already know and can implement in code. For example, do you code with classes, STL, in C, in C++, mixed C/C++, etc? It is for us to know what solutions we can propose you to implement as there are usually many ways to solve the problem.  

Answer 17

Thanks

I followed your s an Waynes advice I have come up with a working program just need to smooth it.

Answer 18

Here is my new code it worked at first ran it a third time and it crashed and still crashes.

Any suggestions??

# include <iostream>
# include <cstdlib>
# include <string>
using namespace std;
//function prototype
void DatePrint(const char *Date);
int main()
{
	
	char Date[20];
	cout<<"Enter a date in the following format mm/dd/yyyy: ";
	cin>>Date;
	DatePrint(Date);
	cout<<endl;
	return 0;
}
void DatePrint(const char *Date)
{
	int month;
	int day;
	int year;
	char mm[3];
	char dd[3];
	char *MonthStr[]={"January", "Febuary", "March",
		               "April", "May", "June", "July",
					   "September", "October", "November",
					   "December"};
	// input array to separate function arrays
	mm[0] = Date[0];
	mm[1] = Date[1];
	mm[2] = '\0';
	dd[0] = Date[3];
	dd[1] = Date[4];
	dd[2] = '\0';
	//int equivalent/conversion
	 
	month = atoi(mm);
	day = atoi(dd);
	year = atoi(Date + 6);
	if (month > 12 || month < 1 || !day || !year) //validation of input
	{
		cout<<"Big dummy follow instructions\n";
	}
	else
		cout<<MonthStr[month - 1]<<" "<<day<<", "<<year<<endl; 
}

Answer 19

caught my error I forgot August in the months

Eveyone thanks for your input..