Qns about getting dates

[student]

Sample code:

cin.getline(date,11,'\n'); (in the format of dd/mm/yyyy)

Qn:I have to validate the date. ( checking if day exists 1<day<31, eg...
)
however this involves abstracting the date into day month and year.
Any advice on how to do this?

Thanks in advance.

[Albert]

"student" <none@email.com> wrote:
>
>Sample code:
>
>cin.getline(date,11,'\n'); (in the format of dd/mm/yyyy)
>
>Qn:I have to validate the date. ( checking if day exists 1<day<31, eg...
>)
>however this involves abstracting the date into day month and year.
>Any advice on how to do this?
>
>Thanks in advance.
>
>you can put the substring dd in an other string

>then you can use function like
int atoi(char*)

try this code
/////////
char date[12];
char D[3];
cin.getline(date,11,'\n');
//get the substring you need you may have better way
for(int i=0;i<2 && date[i]!='\\';i++)
D[i]=date[i];
int day;
///convert the string to int
day= atoi(D);

Good Luck

[Luis]

"student" <none@email.com> wrote:
>
>Sample code:
>
>cin.getline(date,11,'\n'); (in the format of dd/mm/yyyy)
>
>Qn:I have to validate the date. ( checking if day exists 1<day<31, eg...
>)
>however this involves abstracting the date into day month and year.
>Any advice on how to do this?
>
>Thanks in advance.
>
>
>

Hi, here's my suggestion:

#include <cstring>
#include <sstream>
#include <ctime>
#include <iostream>

using namespace std;

class InvalidDate
{
public:
InvalidDate() {}

~InvalidDate(){}

const char * GetError()
{
return "Invalid Date Value";
}

};

class Date
{
int _Day;
int _Mon;
int _Year;

bool ParseDateString(const char *szDateToParse)
{
//szDateToParse expected format MM/DD/YYYY

//NOTE: I'm not checking for leap year. Do it yourself!!!

bool bret = false;

if (szDateToParse &&
strlen(szDateToParse) == 10 &&
szDateToParse[2] == '/' &&
szDateToParse[5] == '/')
{

string s = szDateToParse;

_Mon = atoi(s.substr(0,2).c_str());
_Day = atoi(s.substr(3,2).c_str());
_Year = atoi(s.substr(6, 4).c_str());

bret = Validate();
}

return bret;

}

bool Validate()
{
bool bret;

bret = (_Day >= 1 && _Day <= 31) &&
(_Mon >= 1 && _Mon <= 12) &&
CheckDayOfMonth();

if (bret && _Mon == 2 && _Day > 29)
bret = false;

return bret;


}

bool CheckDayOfMonth()
{
bool bret;
const int _DaysPerMonth[] = {0, 31, 29, 31, 30, 31, 30, 31, 30, 30, 31,
30, 31};

bret = _Day <= _DaysPerMonth[_Mon];

return bret;


}

public:




Date()
{
time_t t;
time(&t);

struct tm *pt = localtime(&t);

_Day = pt->tm_mday;
_Mon = pt->tm_mon+1;
_Year = pt->tm_year+1900;
}

Date(int Day, int Mon, int Year) :_Day(Day),_Mon(Mon),_Year(Year)
{
if (!Validate())
{
throw InvalidDate();
}
}

Date (const char *szDate) //expects a string containing Date in MM/DD/YYYY
format
{
if (!ParseDateString(szDate)) throw InvalidDate();
}

~Date() {}

friend ostream& operator << (ostream& os, const Date& date) // for cout
{
os << date._Mon << "/" << date._Day << "/" << date._Year ;
return os;
}

friend istream& operator >> (istream& is, Date& date) // for cin
{

is >> date._Mon >> date._Day >> date._Year ;

if (!date.Validate()) throw InvalidDate();

return is;
}
};

int main()
{
try
{
char s[11];

cout << "Enter a valid date [MM/DD/YYYY]: ";

cin.getline(s, sizeof s);

Date dt = s; //constructs a date object from a string

cout << "Date: " << dt << endl; //executed only if dt is a valid Date object

Date today; //construct a default Date object

cout << "Today is: " << today << endl;

Date dtInput;

cout << "Enter new date [MM DD YYYY]: "; //build a Date object from standard
input

cin >> dtInput;

cout << dtInput << endl;

Date dt2(2,30,2000); //create invalid date object

cout << "Date: " << dt << endl; //not reached, because an exception will
be thrown

}
catch (InvalidDate id)
{
cout << id.GetError() << endl;
}

return 0;
}


I hope this helps.

Luis