所以，我以为我正在完成我的计划。我编译了它并得到了一堆LNK（2019和2001）错误。
我确实对它们进行了一些研究，一个流行的解决方案是摆脱导致错误的代码。这似乎不完全正确。我试了一下，但没办法。
这是错误分支的文件。
我正在研究如何解决这些错误..我以前从未遇到过LNK错误。
错误：
1＆gt; bankingdriver.obj：错误LNK2019：未解析的外部符号“public：__thiscall Account :: ~Account（void）”（?? 1Account @@ QAE @ XZ）在函数“void __cdecl createTextFile（class std ::）中引用basic_fstream＆gt;＆amp;）“（？createTextFile @@ YAXAAV？$ basic_fstream @ DU？$ char_traits @ D @ std @@@ std @@@ Z）
1＆gt; bankingdriver.obj：错误LNK2019：未解析的外部符号“void __cdecl outputLine（class std :: basic_ostream＆gt;＆amp; class class const＆amp;）”（？outputLine @@ YAXAAV？$ basic_ostream @ DU？$ char_traits @ D @ std @@@ std @@ ABVAccount @@@ Z）在函数“void __cdecl createTextFile（class std :: basic_fstream＆gt;＆amp;）”中引用（？createTextFile @@ YAXAAV？$ basic_fstream @ DU？$ char_traits @ d @ STD @@@ STD @@@ Z）
1＆gt; bankingdriver.obj：错误LNK2019：未解析的外部符号“public：double __thiscall Account :: getBalance（void）”（？getBalance @ Account @@ QAENXZ）在函数“void __cdecl updateRecord（class std :: basic_fstream”）中引用＆gt;＆amp;）“（？updateRecord @@ YAXAAV？$ basic_fstream @ DU？$ char_traits @ D @ std @@@ std @@@ Z）
1＆gt; bankingdriver.obj：错误LNK2019：未解析的外部符号“public：void __thiscall Account :: setAccountNumber（int）”（？setAccountNumber @ Account @@ QAEXH @ Z）在函数“void __cdecl newRecord（class std： ：basic_fstream＆gt;＆amp;）“（？newRecord @@ YAXAAV？$ basic_fstream @ DU？$ char_traits @ D @ std @@@ std @@@ Z）
1＆gt; BankingSystem.obj：错误LNK2001：未解析的外部符号“public：void __thiscall Account :: setAccountNumber（int）”（？setAccountNumber @ Account @@ QAEXH @ Z）
//banking system driver program
#include "BankingSystem.h" // Account class definition
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib> // exit function prototype
using namespace std;
int enterChoice();
void createTextFile( fstream& );
void updateRecord( fstream& );
void newRecord( fstream& );
void deleteRecord( fstream& );
void outputLine( ostream&, const Account & );
int getAccount( const char * const );
enum Choices { PRINT = 1, UPDATE, NEW, DELETE, END };
int main()
{
// open file for reading and writing
fstream inOutCredit( "credit.dat", ios::in | ios::out | ios::binary );
// exit program if fstream cannot open file
if ( !inOutCredit )
{
cerr << "File could not be opened." << endl;
exit ( 1 );
} // end if
int choice; // store user choice
// enable user to specify action
while ( ( choice = enterChoice() ) != END )
{
switch ( choice )
{
case PRINT: // create text file from record file
createTextFile( inOutCredit );
break;
case UPDATE: // update record
updateRecord( inOutCredit );
break;
case NEW: // create record
newRecord( inOutCredit );
break;
case DELETE: // delete existing record
deleteRecord( inOutCredit );
break;
default: // display error if user does not select valid choice
cerr << "Incorrect choice" << endl;
break;
} // end switch
inOutCredit.clear(); // reset end-of-file indicator
} // end while
} // end main
// enable user to input menu choice
int enterChoice()
{
// display available options
std::cout << "\nEnter your choice" << endl
<< "1 - store a formatted text file of accounts" << endl
<< "2 - called \"print.txt\" for printing" << endl
<< "3 - update an account" << endl
<< "4 - add a new account" << endl
<< "5 - delete an account" << endl
<< "6 - end program\n? ";
int menuChoice;
std::cin >> menuChoice; // input menu selection from user
return menuChoice;
} // end function enterChoice
// create formatted text file for printing
void createTextFile( fstream &readFromFile )
{
// create text file
ofstream outPrintFile( "print.txt", ios::out );
// exit program if ofstream cannot create file
if ( !outPrintFile )
{
cerr << "File could not be created." << endl;
exit( 1 );
} // end if
outPrintFile << left << setw( 10 ) << "Account" << setw( 16 )
<< "Last Name" << setw( 11 ) << "First Name" << right
<< setw( 10 ) << "Balance" << endl;
// set file-position pointer to beginning of readFromFile
readFromFile.seekg( 0 );
// read first record from record file
Account client;
readFromFile.read( reinterpret_cast< char * >( &client ),
sizeof( Account ) );
// copy all records from record file into text file
while ( !readFromFile.eof() )
{
// write single record to text file
if ( client.getAccountNumber() != 0 ) // skip empty records
outputLine( outPrintFile, client );
// read next record from record file
readFromFile.read( reinterpret_cast< char * >( &client ),
sizeof( Account ) );
} // end while
} // end function createTextFile
// update balance in record
void updateRecord( fstream &updateFile )
{
// obtain number of account to update
int accountNumber = getAccount( "Enter account to update" );
// move file-position pointer to correct record in file
updateFile.seekg( ( accountNumber - 1 ) * sizeof( Account ) );
// read first record from file
Account client;
updateFile.read( reinterpret_cast< char * >( &client ),
sizeof( Account ) );
// update record
if ( client.getAccountNumber() != 0 )
{
outputLine( cout, client ); // display the record
// request user to specify transaction
std::cout << "\nEnter charge (+) or payment (-): ";
double transaction; // charge or payment
std::cin >> transaction;
// update record balance
double oldBalance = client.getBalance();
client.setBalance( oldBalance + transaction );
outputLine( cout, client ); // display the record
// move file-position pointer to correct record in file
updateFile.seekp( ( accountNumber - 1 ) * sizeof( Account ) );
// write updated record over old record in file
updateFile.write( reinterpret_cast< const char * >( &client ),
sizeof( Account ) );
} // end if
else // display error if account does not exist
cerr << "Account #" << accountNumber
<< " has no information." << endl;
} // end function updateRecord
// create and insert record
void newRecord( fstream &insertInFile )
{
// obtain number of account to create
int accountNumber = getAccount( "Enter new account number" );
// move file-position pointer to correct record in file
insertInFile.seekg( ( accountNumber - 1 ) * sizeof( Account ) );
// read record from file
Account client;
insertInFile.read( reinterpret_cast< char * >( &client ),
sizeof( Account ) );
// create record, if record does not previously exist
if ( client.getAccountNumber() == 0 )
{
string lastName;
string firstName;
double balance;
// user enters last name, first name and balance
std:: cout << "Enter lastname, firstname, balance\n? ";
std::cin >> lastName;
std::cin >> firstName;
std::cin >> balance;
// use values to populate account values
client.setLastName( lastName );
client.setFirstName( firstName );
client.setBalance( balance );
client.setAccountNumber( accountNumber );
// move file-position pointer to correct record in file
insertInFile.seekp( ( accountNumber - 1 ) * sizeof( Account ) );
// insert record in file
insertInFile.write( reinterpret_cast< const char * >( &client ),
sizeof( Account ) );
} // end if
else // display error if account already exists
cerr << "Account #" << accountNumber
<< " already contains information." << endl;
} // end function newRecord
// delete an existing record
void deleteRecord( fstream &deleteFromFile )
{
// obtain number of account to delete
int accountNumber = getAccount( "Enter account to delete" );
// move file-position pointer to correct record in file
deleteFromFile.seekg( ( accountNumber - 1 ) * sizeof( Account ) );
// read record from file
Account client;
deleteFromFile.read( reinterpret_cast< char * >( &client ),
sizeof( Account ) );
// delete record, if record exists in file
if ( client.getAccountNumber() != 0 )
{
Account blankClient; // create blank record
// move file-position pointer to correct record in file
deleteFromFile.seekp( ( accountNumber - 1 ) *
sizeof( Account ) );
// replace existing record with blank record
deleteFromFile.write(
reinterpret_cast< const char * >( &blankClient ),
sizeof( Account ) );
std::cout << "Account #" << accountNumber << " deleted.\n";
} // end if
else // display error if record does not exist
cerr << "Account #" << accountNumber << " is empty.\n";
} // end deleteRecord
// display single record
void outputLine( ostream &output,Account &record )
{
output << left << setw( 10 ) << record.getAccountNumber()
<< setw( 16 ) << record.getLastName()
<< setw( 11 ) << record.getFirstName()
<< setw( 10 ) << setprecision( 2 ) << right << fixed
<< showpoint << record.getBalance() << endl;
} // end function outputLine
// obtain account-number value from user
int getAccount( const char * const prompt )
{
int accountNumber;
// obtain account-number value
do
{
std::cout << prompt << " (1 - 100): ";
std::cin >> accountNumber;
} while ( accountNumber < 1 || accountNumber > 100 );
return accountNumber;
} // end function getAccount
答案 0 :(得分：0)
您应该检查'BankingSystem.h'和帐户类。 有错误意味着这些函数解决了编译器找不到的'getBalance'，所以你应该首先检查这些函数是否存在，然后你必须确保你的项目中已经包含了BankingSystem.lib文件。
答案 1 :(得分：0)
这些错误意味着定义了函数，但未声明。因此编译器已经看到了函数的定义，但函数尚未在项目中实现。也许它们存在于库中，或者您缺少项目中的CPP文件。
答案 2 :(得分：0)
编译器获取源文件并生成目标文件。链接器获取所有目标文件（和库）并生成可执行文件（或DLL）。您收到的消息表明您忘记为这些函数编写代码，或者您忘记在链接步骤中包含必要的目标文件或库。
这似乎是MS VC ++。如果您正在使用命令行工具（或使用命令行工具的NMAKE之类的东西），那么请注意cl命令将默认编译然后尝试链接生成的文件。这适用于快速实验，但在项目跨多个源文件时很少有用。
我的猜测是你只是想编译一个文件，cl也试图为你链接它。要使cl只执行编译步骤，请使用/c选项。然后，一旦将所有源文件编译成目标文件，就可以将它们作为单独的步骤与link命令链接，并列出所有目标文件。
如果您使用Visual Studio IDE进行构建，则需要将所有源文件添加到同一个项目中。