C++ || Struct – Add One Day To Today’s Date Using A Struct

January 18, 2012 admin No comments

This program displays more practice using the structure data type, and is very similar to another program which was previously discussed here.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Functions Passing a Value By Reference Integer Arrays Structures Constant Variables Boolean Expressions

This program utilizes a struct, which is very similar to the class concept. This program first prompts the user to enter the current date in mm/dd/yyyy format. Upon obtaining the date from the user, the program then uses a struct implementation to simply add one day to the date which was entered by the user. If the day that was entered into the program by the user falls on the end of the month, the program will”roll over” the incremented date into the next month. If the user enters 12/31/2012, the program will “roll over” the incremented date into the next calendar year.

NOTE: On some compilers, you may have to add #include < cstdlib> in order for the code to compile.





		
		
			Whats Today's Date?
			
C++
			
			#include <iostream> 
using namespace std;

// struct declaration
struct Date
{
	int month;
	int day;
	int year;
};

// constants which do not change
// specifies the max values for each variable
const int MAX_DAYS = 31;
const int MAX_MONTHS = 12; 

// function prototypes
bool IsDateValid(Date dateVal);
void CalcNextDay(Date &dateVal);

int main()
{
	// initialize the structure: month, day, year
	Date dateVal = {1,18,2012};
	char backSlash = '/'; // this is a 'placeholder' variable
	
	// obtain information from user
	cout << "Please enter today's date in mm/dd/yyyy format: ";
	cin >> dateVal.month >> backSlash >> dateVal.day >> backSlash >> dateVal.year;
	
	// Checks to see if user entered valid data
	if (IsDateValid(dateVal) == false)
	{
		cout << "Invalid input...nProgram exiting...." << endl;
		exit(EXIT_FAILURE);
	} 
	
	// function declaration which calculates the next day
	CalcNextDay(dateVal);

	// display updated data to user
	cout << "The next day is " << dateVal.month << "/" << dateVal.day << "/" << dateVal.year <<endl; 
	
	return 0;
}// end of main

	// this function checks to see if the user inputted valid data
bool IsDateValid(Date dateVal)
{
     // checks to see if user inputted data falls between the specified
     // const variables as declared above
     if ((dateVal.day >= 1 && dateVal.day <= MAX_DAYS)
          &&(dateVal.month >= 1 && dateVal.month <= MAX_MONTHS))
     {
          return true;
     }
     else
     {
          return false;
     }
}// end of IsDateValid 

	// this calculates the next day & updates values via reference
void CalcNextDay(Date &dateVal)
{
	// int array which holds the max date each month has
	// from January to December
	int maxDays[12]={31,28,31,30,31,30,31,31,30,31,30,31};
	
	// bool which lets the program know if the month the
	// user entered is a max month for the specific month
	// the user inputted
	bool maxDay = false;
	
	// checks to see if user inputted day is a max date from the 
	// above array for the currently selected month which 
	// was entered by the user
	if(dateVal.day == maxDays[dateVal.month-1])
	{
		dateVal.day = 1;
		++dateVal.month;
		maxDay = true;
	}

	// checks to see if user inputted a valid date
	// for the currently selected month
	else if (dateVal.day > maxDays[dateVal.month-1])
	{
		cout << "Invalid day input - There is no such date for the selected month.nProgram exiting...." << endl;
		exit(EXIT_FAILURE);
	} 

	// if user didnt enter a max date, and the date is valid, increment the day
	else
	{
		++dateVal.day;
	}

	// if the date is 12/31/yyyy
	// increment to the next year
	if ((dateVal.month > 12)  && maxDay == true)
	{
		dateVal.month = 1;
		++dateVal.year;
	}
}// http://programmingnotes.org/
			
				
					
				
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						#include <iostream> 
using namespace std;
 
// struct declaration
struct Date
{
	int month;
	int day;
	int year;
};
 
// constants which do not change
// specifies the max values for each variable
const int MAX_DAYS = 31;
const int MAX_MONTHS = 12; 
 
// function prototypes
bool IsDateValid(Date dateVal);
void CalcNextDay(Date &dateVal);
 
int main()
{
	// initialize the structure: month, day, year
	Date dateVal = {1,18,2012};
	char backSlash = '/'; // this is a 'placeholder' variable
	
	// obtain information from user
	cout << "Please enter today's date in mm/dd/yyyy format: ";
	cin >> dateVal.month >> backSlash >> dateVal.day >> backSlash >> dateVal.year;
	
	// Checks to see if user entered valid data
	if (IsDateValid(dateVal) == false)
	{
		cout << "Invalid input...nProgram exiting...." << endl;
		exit(EXIT_FAILURE);
	} 
	
	// function declaration which calculates the next day
	CalcNextDay(dateVal);
 
	// display updated data to user
	cout << "The next day is " << dateVal.month << "/" << dateVal.day << "/" << dateVal.year <<endl; 
	
	return 0;
}// end of main
 
	// this function checks to see if the user inputted valid data
bool IsDateValid(Date dateVal)
{
     // checks to see if user inputted data falls between the specified
     // const variables as declared above
     if ((dateVal.day >= 1 && dateVal.day <= MAX_DAYS)
          &&(dateVal.month >= 1 && dateVal.month <= MAX_MONTHS))
     {
          return true;
     }
     else
     {
          return false;
     }
}// end of IsDateValid 
 
	// this calculates the next day & updates values via reference
void CalcNextDay(Date &dateVal)
{
	// int array which holds the max date each month has
	// from January to December
	int maxDays[12]={31,28,31,30,31,30,31,31,30,31,30,31};
	
	// bool which lets the program know if the month the
	// user entered is a max month for the specific month
	// the user inputted
	bool maxDay = false;
	
	// checks to see if user inputted day is a max date from the 
	// above array for the currently selected month which 
	// was entered by the user
	if(dateVal.day == maxDays[dateVal.month-1])
	{
		dateVal.day = 1;
		++dateVal.month;
		maxDay = true;
	}
 
	// checks to see if user inputted a valid date
	// for the currently selected month
	else if (dateVal.day > maxDays[dateVal.month-1])
	{
		cout << "Invalid day input - There is no such date for the selected month.nProgram exiting...." << endl;
		exit(EXIT_FAILURE);
	} 
 
	// if user didnt enter a max date, and the date is valid, increment the day
	else
	{
		++dateVal.day;
	}
 
	// if the date is 12/31/yyyy
	// increment to the next year
	if ((dateVal.month > 12)  && maxDay == true)
	{
		dateVal.month = 1;
		++dateVal.year;
	}
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output:
Note: The code was compiled 6 separate times to display the different outputs its able to produce

Please enter today's date in mm/dd/yyyy format: 1/18/2012 The next day is 1/19/2012 -------------------------------------------------------------------
Please enter today's date in mm/dd/yyyy format: 7/31/2012 The next day is 8/1/2012 ------------------------------------------------------------------- Please enter today's date in mm/dd/yyyy format: 2/28/2012 The next day is 3/1/2012 ------------------------------------------------------------------- Please enter today's date in mm/dd/yyyy format: 13/5/2012 Invalid input... Program exiting.... ------------------------------------------------------------------- Please enter today's date in mm/dd/yyyy format: 2/31/2012 Invalid day input - There is no such date for the selected month. Program exiting.... -------------------------------------------------------------------
Please enter today's date in mm/dd/yyyy format: 12/31/2012 The next day is 1/1/2013

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Posted in: Advanced, C++ Tags: array, c++, const, date, if/else, Output, Struct

C++ || Struct – Add One Day To Today’s Date Using A Struct

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