please help with this c++ program

[computer nazi]

Please help me with this program. It is supposed to determine the number of days between two dates inputted by the user while also taking into account leap years. This program also has to do error checking. It must include at least "if" statement, at least 2 function, at least 1 loop structure, at least 1 switch statement. This is what I have so far but I am completely lost.

#include<iostream>
#include<iomanip>
#include<string>
using namespace std;

int main()
{
 	int day, month, date;

	
     cin >> month;
		   do
		       {
cout <<"\nPlease enter your birthday in the following format: MM-DD-YYY" << endl << endl;
             //totally lost on this part
		   	 	  cin >> month;
		   	 	  cin.get(ch);
		   	 	  cin >> date;
		   	 	  cin.get(ch)
		   	 	  cin >> year;
		   	 	  cout << endl;
		   	 	  
		       } while ((month <= 12) || (month >= 1));
	 			  
	 			   cout <<"Please enter a valid date" << endl;
	 			      
	 			 cin.get(ch);
	 			 
	 			 cin >> day;
 			      if ((day < 31) || (day >1))
 			      else 
 			      	   cout <<"Please enter a valid date" << endl;
	 			 cin.get(ch);
	 			 cin >> year;
	 			 
	 			 
	 			 //not really sure what this does..
    system("pause");
    return 0;

}

This is as far as I've gotten. Please, please help me with this.

[DimitriuS]

#include<iostream>

using namespace std;

/*-- Function prototypes--*/
int POS_INT_TRANS(char* system_number);
bool Switch_ERROR_message_ALERT(int d,int m,int y);

unsigned long int GeT_The_NumbER_of_DAYS();//up to 4.294.967.296 days , approximately 11.767.033 years (365 days per year).

/*--global variables--*/
char date_buf[13];
char temp_day[3];
char temp_month[3];
char temp_year[6];

int day1,day2;
int month1,month2;
int year1,year2;

main( int argc , char* argv[] )/*--this program does not use the main arguments.*/
{
 bool Sc=0;
 char ch1,ch2;

 do
 {
  cout<<"Enter the first date in the following format DD-MM-YYYY(for Europe)--:";
  cin.get(date_buf[0]);//--in case the user press 'enter' without giving any other data
  
  if( date_buf[0]==10 )
  {
   cout<<"--ERROR--Wrong format of the given data."<<endl;
   continue;
  }
  
  cin.get( date_buf+1,11 );

  for(int i=0; i<2; i++)
  {
   temp_day[i]=date_buf[i];
   temp_day[i+1]='\0';
  } 
  for(int c=0,i=3; i<5; c++,i++)
  {
   temp_month[c]=date_buf[i];
   temp_month[c+1]='\0';
  }
  for(int c=0,i=6; i<10; c++,i++)
  {
   temp_year[c]=date_buf[i];
   temp_year[c+1]='\0';
  }
  day1  =POS_INT_TRANS( temp_day );
  month1=POS_INT_TRANS( temp_month );
  year1 =POS_INT_TRANS( temp_year );

  Sc=Switch_ERROR_message_ALERT(day1,month1,year1);
  
  cin.ignore(4096,'\n');
 }
 while(!Sc);
/*------end of first input block-------------------------------------------------------------------*/
/***************************************************************************************************/
/*--------second input block-----------------------------------------------------------------------*/
/***************************************************************************************************/
 Sc=0;
 
 do
 {
  cout<<"Enter the second date (the way you did previously)---------------------:";
  cin.get(date_buf[0]);//--in case the user press 'enter' without giving any other data
  
  if( date_buf[0]==10 )
  {
   cout<<"--ERROR--Wrong format of the given data."<<endl;
   continue;
  }  
  cin.get( date_buf+1,11 );

  for(int i=0; i<2; i++)
  {
   temp_day[i]=date_buf[i];
   temp_day[i+1]='\0';
  }
  
  for(int c=0,i=3; i<5; c++,i++)
  {
   temp_month[c]=date_buf[i];
   temp_month[c+1]='\0';
  }
 
  for(int c=0,i=6; i<10; c++,i++)
  {
   temp_year[c]=date_buf[i];
   temp_year[c+1]='\0';
  } 
  day2  =POS_INT_TRANS( temp_day ); 
  month2=POS_INT_TRANS( temp_month );
  year2 =POS_INT_TRANS( temp_year );

  Sc=Switch_ERROR_message_ALERT(day2,month2,year2);
  
  cin.ignore(4096,'\n');
 }
 while(!Sc);
/*------end of second input block-------------------------------------------------------------------*/
/*********************************************************************************************/
 system("clear");
 cout<<"---***************************---"<<endl;
 cout<<"---******----RESULTS----******---"<<endl;
 cout<<"---***************************---"<<endl;
 cout<<"---------------------------------"<<endl;
 cout<<"---OldER DaTE--:"<<day1<<"-"<<month1<<"-"<<year1<<endl;
 cout<<"---NewER  DaTE--:"<<day2<<"-"<<month2<<"-"<<year2<<endl;

 unsigned long int TOTAL_DAYS=GeT_The_NumbER_of_DAYS();//--call of GeT_The_NumbER_of_DAYS() routine
 cout<<"----****--"<<TOTAL_DAYS<<" days between these two dates!!---"<<endl;
 cout<<"\n-------EnD OF ThE PRogrAM!!!---ByE----"<<endl;
}
/*------END OF MAIN FUNCTION BLOCK------------------------------------------------------------------*/
/****************************************************************************************************/
/*-----------------FUNCTIONS FIELD------------------------------------------------------------------*/
/****************************************************************************************************/
/*-----Function GeT_The_NumbER_of_DAYS------*/
unsigned long int GeT_The_NumbER_of_DAYS()
{
 int m_day1,m_month1,m_year1,m_day2,m_month2,m_year2;
 int C,month_CounteR;
 int TotaL_DAYS=0;
 
 if( (year1<year2) || ((year1==year2) && (month1<month2)) || ((year1==year2) && (month1==month2) && (day1<=day2)) )
 {
  m_day1=day1;
  m_day2=day2;
  m_month1=month1;
  m_month2=month2;
  m_year1=year1;
  m_year2=year2;
 }
 if( (year1>year2) || ((year1==year2) && (month1>month2)) || ((year1==year2) && (month1==month2) && (day1>day2)) )
 {
  m_day1=day2;
  m_day2=day1;
  m_month1=month2;
  m_month2=month1;
  m_year1=year2;
  m_year2=year1;
 }

 for(int y=m_year1; y<=m_year2; y++)
 {
  if( y==m_year1 )
  {
   C=m_month1;
   month_CounteR=12;
  }
  if( y==m_year2 )
  {
   month_CounteR=m_month2-1;
  }

  for(C; C<=month_CounteR; C++)
  {
   if( ((C%2==1)&&(C!=9)&&(C!=11)) || C==8 || C==10 || C==12 )//-January-March-May-July-August-October-December-
   {
    TotaL_DAYS=TotaL_DAYS+31;
    continue;
   } 
 
   if( (C==2)&&(y%4==0) )//-February and leap year-
   {
    TotaL_DAYS=TotaL_DAYS+29; 
    continue ;
   } 
  
   if( (C==2)&&(y%4!=0) )//-February and no leap year-
   { 
    TotaL_DAYS=TotaL_DAYS+28;
    continue;
   }
  
   TotaL_DAYS=TotaL_DAYS+30;//-Normal-*-April-June-September-November-
  }//--end of internal loop
  //cout<<TotaL_DAYS<<endl;
  C=1;
 }//--end of external loop
 
 TotaL_DAYS=TotaL_DAYS-m_day1+m_day2;

 return TotaL_DAYS;
}
/*################################################################*/
/*-----Function POS_INT_TRANS------*/
int POS_INT_TRANS(char* system_number)/*--this function transforms a string ONLY into a POSITIVE integer.-only 0-9 characters accepted*/
{
 int sum=0;
 if(system_number==0)
 {
  return -1;
 }

 for(int i=0; system_number[i]!='\0'; i++)
 {
  if( system_number[i]<48 || system_number[i]>57 )
  {
   return -1;//no arithmetic characters
  }       
 }
 sum=atoi(system_number);
 return sum;
}
/*################################################################*/
/*-----Function switch_error_message_alert------*/
bool Switch_ERROR_message_ALERT(int d,int m,int y)
{
 int control=-1;

 if(y<0)
 control=1;
 if(m>12)
 control=2;
 if(m<1)
 control=3;
 if(d>31)
 control=4;
 if(d<1)
 control=5;
 if(m==2/*February*/ && d>29)
 control=6;
 if(m==2 && (y%4)!=0/*no leap year*/ && d==29)
 control=7;
 if(m==4/*April*/ && d==31)
 control=8;
 if(m==6/*June*/ &&d==31)
 control=9;
 if(m==9/*September*/ && d==31)
 control=10;
 if(m==11/*November*/ && d==31)
 control=11;

 if(date_buf[0]==45||date_buf[1]==45||date_buf[2]!=45||date_buf[3]==45||date_buf[4]==45||date_buf[5]!=45||date_buf[6]==45||date_buf[6]==0||date_buf[7]==45||date_buf[7]==0||date_buf[8]==45||date_buf[8]==0||date_buf[9]==45||date_buf[9]==0||date_buf[10]!=0)
 {
  control=0;
 }

 switch( control )
 {
  case  0: cout<<"--ERROR--Wrong format of the given data."<<endl; break;
  case  1: cout<<"--ERROR--The year you gave is invalid.Year should be >0 and <=9999."<<endl; return 0; break;
  case  2: cout<<"--ERROR--The month you gave is invalid.Month should be >0 and <13."<<endl; return 0; break;
  case  3: cout<<"--ERROR--The month you gave is invalid.Month should be >0 and <13."<<endl; return 0; break;
  case  4: cout<<"--ERROR--The day you gave is too large.Day should be >0 and <32."<<endl; return 0; break;
  case  5: cout<<"--ERROR--The day you gave is invalid.Day should be >0 and <32."<<endl; return 0; break;
  case  6: cout<<"--ERROR--There is no such day["<<d<<"] on February."<<endl; return 0; break;
  case  7: cout<<"--ERROR--The year["<<y<<"] is not a leap one.Thus,29th February "<<y<<" is not a valid date."<<endl; return 0; break;
  case  8: cout<<"--ERROR--April has just 30 days."<<endl; return 0; break;
  case  9: cout<<"--ERROR--June has just 30 days."<<endl; return 0; break;
  case 10: cout<<"--ERROR--September has just 30 days."<<endl; return 0; break;
  case 11: cout<<"--ERROR--November has just 30 days."<<endl; return 0; break;
  
  default : return 1; break; 
 }
}

[DimitriuS]

It would be enough for me a simple "ThanK YoU",honestly.
Look,this program,as for the number of times I have tested,works perfect.I have tested its validity by using various data inputs.The source code covers all the structures you were supposed to use(Switch,if-else,loops,functions,...etc).I apologise both for the fact that the code lacks rich comments(I hope you deal with the parts being difficult to be understood) and for the fact that ,because I m a European(Im from GreeCE),I have been used to dealing with this date format:dd-mm-yyyy and not with the american one:mm-dd-yyyy.Once you completely understand the code you will be able to change just a few lines of code in order to make this program support the american date format.