fatal error LNK1120: 1 unresolved externals 如何解决这个问题？

[jibee]

#ifndef HEAD_H
#define HEAD_H

class Date {
public:
Date ( int = 1 , int = 1, int = 1990 );
void print() const;
~Date();

private:

int month;
int day;
int year;
int checkDay( int ) const;

};

#endif


#include <iostream>

using std::cout;
using std::endl;

#include "head.h"

Date::Date( int mn, int dy, int yr)
{
if ( mn > 0 && mn <=12 )
month = mn;
else {
month = 1;
cout << "Month " << mn << " invalid. Set to month 1.\n";
}

year = yr;
day = checkDay ( dy );

cout << "Date object constructor for date ";
print ();
cout << endl;
}

void Date::print() const
{

const char *monptr[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
cout << monptr[month-1] <<" " << year << endl;
cout << month << '/' << day << '/' << year <<endl;
cout << monptr[month-1] << " " << day << ',' << " " << year <<endl;

}

Date::~Date()
{
cout << "Date object destructor for date ";
print();
cout <<endl;
}

int Date::checkDay ( int testDay ) const
{
const int daysPerMonth[ 13 ] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
if ( testDay > 0 && testDay <= daysPerMonth[ month ] )
return testDay;
if ( month == 2 && testDay == 29 && ( year % 400 == 0 || ( (year % 4 == 0) && (year % 100 != 0))))
return testDay;

cout << "Day " << testDay << " invalid. Set to day 1.\n";
return 1;
}

[老K（郭云开）]

我编译过，没有问题。是不是编译器的Include path 和Library path 有问题。

[我啃]

main函数？

[老K（郭云开）]

//Head.h
#ifndef HEAD_H
#define HEAD_H
class CDate{
public:
CDate ( int = 1 , int = 1, int = 1990 );
void print() const;
~CDate();

private:

int month;
int day;
int year;
int checkDay( int ) const;

};

#endif

[老K（郭云开）]

//Head.cpp------------------------------------------------------------------------
#pragma hdrstop

#include "Head.h"

//---------------------------------------------------------------------------

#pragma package(smart_init)
#include <iostream>

using std::cout;
using std::endl;
CDate::CDate( int mn, int dy, int yr)
{
if ( mn > 0 && mn <=12 )
month = mn;
else {
month = 1;
cout << "Month " << mn << " invalid. Set to month 1.\n";
}

year = yr;
day = checkDay ( dy );

cout << "Date object constructor for date ";
print ();
cout << endl;
}

void CDate::print() const
{

const char *monptr[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
cout << monptr[month-1] <<" " << year << endl;
cout << month << '/' << day << '/' << year <<endl;
cout << monptr[month-1] << " " << day << ',' << " " << year <<endl;

}

CDate::~CDate()
{
cout << "Date object destructor for date ";
print();
cout <<endl;
}

int CDate::checkDay ( int testDay ) const
{
const int daysPerMonth[ 13 ] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
if ( testDay > 0 && testDay <= daysPerMonth[ month ] )
return testDay;
if ( month == 2 && testDay == 29 && ( year % 400 == 0 || ( (year % 4 == 0) && (year % 100 != 0))))
return testDay;

cout << "Day " << testDay << " invalid. Set to day 1.\n";
return 1;
}

[老K（郭云开）]

//main------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

//---------------------------------------------------------------------------
#include "Head.h"
#include <stdio.h>

#pragma argsused
int main(int argc, char* argv[])
{
CDate date;
date.print();
getchar();
return 0;
}
//---------------------------------------------------------------------------

[老K（郭云开）]

发生该连接错误主要是因为Date和SysUtils：：Date（）命名冲突。

[老K（郭云开）]

所以我把Date命名为CDate，