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| author | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
|---|---|---|
| committer | Sven Eisenhauer <sven@sven-eisenhauer.net> | 2023-11-10 15:11:48 +0100 |
| commit | 33613a85afc4b1481367fbe92a17ee59c240250b (patch) | |
| tree | 670b842326116b376b505ec2263878912fca97e2 /Bachelor/Prog2/Codebeispiele/4_ch14/Fig14_15.cpp | |
| download | Studium-33613a85afc4b1481367fbe92a17ee59c240250b.tar.gz Studium-33613a85afc4b1481367fbe92a17ee59c240250b.tar.bz2 | |
Diffstat (limited to 'Bachelor/Prog2/Codebeispiele/4_ch14/Fig14_15.cpp')
| -rw-r--r-- | Bachelor/Prog2/Codebeispiele/4_ch14/Fig14_15.cpp | 331 |
1 files changed, 331 insertions, 0 deletions
diff --git a/Bachelor/Prog2/Codebeispiele/4_ch14/Fig14_15.cpp b/Bachelor/Prog2/Codebeispiele/4_ch14/Fig14_15.cpp new file mode 100644 index 0000000..da2ef2e --- /dev/null +++ b/Bachelor/Prog2/Codebeispiele/4_ch14/Fig14_15.cpp @@ -0,0 +1,331 @@ +// Fig. 14.15: fig14_15.cpp
+// This program reads a random access file sequentially, updates
+// data previously written to the file, creates data to be placed
+// in the file, and deletes data previously in the file.
+#include <iostream>
+
+using std::cout;
+using std::cerr;
+using std::cin;
+using std::endl;
+using std::ios;
+using std::left;
+using std::right;
+using std::fixed;
+using std::showpoint;
+
+#include <fstream>
+
+using std::ofstream;
+using std::ostream;
+using std::fstream;
+
+#include <iomanip>
+
+using std::setw;
+using std::setprecision;
+
+#include <cstdlib>
+#include "clientData.h" // ClientData class definition
+
+int enterChoice();
+void printRecord( fstream& );
+void updateRecord( fstream& );
+void newRecord( fstream& );
+void deleteRecord( fstream& );
+void outputLine( ostream&, const ClientData & );
+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 );
+
+ // exit program if fstream cannot open file
+ if ( !inOutCredit ) {
+ cerr << "File could not be opened." << endl;
+ exit ( 1 );
+
+ } // end if
+
+ int choice;
+
+ // enable user to specify action
+ while ( ( choice = enterChoice() ) != END ) {
+
+ switch ( choice ) {
+
+ // create text file from record file
+ case PRINT:
+ printRecord( inOutCredit );
+ break;
+
+ // update record
+ case UPDATE:
+ updateRecord( inOutCredit );
+ break;
+
+ // create record
+ case NEW:
+ newRecord( inOutCredit );
+ break;
+
+ // delete existing record
+ case DELETE:
+ deleteRecord( inOutCredit );
+ break;
+
+ // display error if user does not select valid choice
+ default:
+ cerr << "Incorrect choice" << endl;
+ break;
+
+ } // end switch
+
+ inOutCredit.clear(); // reset end-of-file indicator
+
+ } // end while
+
+ return 0;
+
+} // end main
+
+// enable user to input menu choice
+int enterChoice()
+{
+ // display available options
+ cout << "\nEnter your choice" << endl
+ << "1 - store a formatted text file of accounts" << endl
+ << " called \"print.txt\" for printing" << endl
+ << "2 - update an account" << endl
+ << "3 - add a new account" << endl
+ << "4 - delete an account" << endl
+ << "5 - end program\n? ";
+
+ int menuChoice;
+ cin >> menuChoice; // receive choice from user
+
+ return menuChoice;
+
+} // end function enterChoice
+
+// create formatted text file for printing
+void printRecord( 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 record file
+ readFromFile.seekg( 0 );
+
+ // read first record from record file
+ ClientData client;
+ readFromFile.read( reinterpret_cast< char * >( &client ),
+ sizeof( ClientData ) );
+
+ // copy all records from record file into text file
+ while ( !readFromFile.eof() ) {
+
+ // write single record to text file
+ if ( client.getAccountNumber() != 0 )
+ outputLine( outPrintFile, client );
+
+ // read next record from record file
+ readFromFile.read( reinterpret_cast< char * >( &client ),
+ sizeof( ClientData ) );
+
+ } // end while
+
+} // end function printRecord
+
+// 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( ClientData ) );
+
+ // read first record from file
+ ClientData client;
+ updateFile.read( reinterpret_cast< char * >( &client ),
+ sizeof( ClientData ) );
+
+ // update record
+ if ( client.getAccountNumber() != 0 ) {
+ outputLine( cout, client );
+
+ // request user to specify transaction
+ cout << "\nEnter charge (+) or payment (-): ";
+ double transaction; // charge or payment
+ cin >> transaction;
+
+ // update record balance
+ double oldBalance = client.getBalance();
+ client.setBalance( oldBalance + transaction );
+ outputLine( cout, client );
+
+ // move file-position pointer to correct record in file
+ updateFile.seekp(
+ ( accountNumber - 1 ) * sizeof( ClientData ) );
+
+ // write updated record over old record in file
+ updateFile.write(
+ reinterpret_cast< const char * >( &client ),
+ sizeof( ClientData ) );
+
+ } // end if
+
+ // display error if account does not exist
+ else
+ 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( ClientData ) );
+
+ // read record from file
+ ClientData client;
+ insertInFile.read( reinterpret_cast< char * >( &client ),
+ sizeof( ClientData ) );
+
+ // create record, if record does not previously exist
+ if ( client.getAccountNumber() == 0 ) {
+
+ char lastName[ 15 ];
+ char firstName[ 10 ];
+ double balance;
+
+ // user enters last name, first name and balance
+ cout << "Enter lastname, firstname, balance\n? ";
+ cin >> setw( 15 ) >> lastName;
+ cin >> setw( 10 ) >> firstName;
+ 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( ClientData ) );
+
+ // insert record in file
+ insertInFile.write(
+ reinterpret_cast< const char * >( &client ),
+ sizeof( ClientData ) );
+
+ } // end if
+
+ // display error if account previously exists
+ else
+ 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( ClientData ) );
+
+ // read record from file
+ ClientData client;
+ deleteFromFile.read( reinterpret_cast< char * >( &client ),
+ sizeof( ClientData ) );
+
+ // delete record, if record exists in file
+ if ( client.getAccountNumber() != 0 ) {
+ ClientData blankClient;
+
+ // move file-position pointer to correct record in file
+ deleteFromFile.seekp( ( accountNumber - 1 ) *
+ sizeof( ClientData ) );
+
+ // replace existing record with blank record
+ deleteFromFile.write(
+ reinterpret_cast< const char * >( &blankClient ),
+ sizeof( ClientData ) );
+
+ cout << "Account #" << accountNumber << " deleted.\n";
+
+ } // end if
+
+ // display error if record does not exist
+ else
+ cerr << "Account #" << accountNumber << " is empty.\n";
+
+} // end deleteRecord
+
+// display single record
+void outputLine( ostream &output, const ClientData &record )
+{
+ output << left << setw( 10 ) << record.getAccountNumber()
+ << setw( 16 ) << record.getLastName().data()
+ << setw( 11 ) << record.getFirstName().data()
+ << 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 {
+ cout << prompt << " (1 - 100): ";
+ cin >> accountNumber;
+
+ } while ( accountNumber < 1 || accountNumber > 100 );
+
+ return accountNumber;
+
+} // end function getAccount
+
+/**************************************************************************
+ * (C) Copyright 1992-2003 by Deitel & Associates, Inc. and Prentice *
+ * Hall. All Rights Reserved. *
+ * *
+ * DISCLAIMER: The authors and publisher of this book have used their *
+ * best efforts in preparing the book. These efforts include the *
+ * development, research, and testing of the theories and programs *
+ * to determine their effectiveness. The authors and publisher make *
+ * no warranty of any kind, expressed or implied, with regard to these *
+ * programs or to the documentation contained in these books. The authors *
+ * and publisher shall not be liable in any event for incidental or *
+ * consequential damages in connection with, or arising out of, the *
+ * furnishing, performance, or use of these programs. *
+ *************************************************************************/
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