1. STARTING OUT WITH STARTING OUT WITH Class 15 Honors

2. 2 Understand some common file I/O functions Set up a program for writing to a file Read information from a file Objectives

3. 3 3 Steps to Use a File The file must be opened. If the file does not exist, opening it means creating it. Information is then saved to the file, read from the file, or both. When the program is finished using the file, the file must be closed. P. 701

4. 4 File Name and ExtensionFile Contents MYPROG.BASBASIC Program MENU.BATDOS Batch File INSTALL.DOCDocumentation File CRUNCH.EXEExecutable File GAMES.GRPWindows Group File BOB.HTMLHTML 3DMODEL. JAVAjava prog. or applet INVENT.OBJObject File PROG1.PRJBorland C++ Porj. File ANSI.SYSSys. Device Driver README.TXTText File CLIENTS.DAT P. 706 Table 12-4

5. 5 Writing Information to a File File: In Memory Variables: X Y Z 10 2540 10 25 40 Data is copied from variables into the file

6. 6 Reading Information from a File File: In Memory Variables: X Y Z 10 2540 10 25 40 Data is copied from the file into variables

7. 7 File Stream Data Type ofstream Description Output File Stream. This data type can be used to create files and write information to them. With the ofstream data type, information may only be copied from variables to the file, but not vice-versa. P. 700 Table 12-1

8. 8 File Stream Data Type ifstream Description Input File Stream. This data type can be used to read information from files into memory. With the ifstream data type, information may only be copied from the file into variables, not but vice-versa. P. 700 Table 12-1

9. 9 File Stream Data Type fstream Description File Stream. This data type can be used to create files, write information to them, and read information from them. With the fstream data type, information may be copied from variables into a file, or from a file into variables. P. 700 Table 12-1

10. 10 ofstream outClientFile(“clients.dat”, ios::out); if (!outClientFile) { cerr<<“File could not be opened” << endl; exit (1);// prototype in stdlib }

11. 11 ofstream outclientFile(“clients.dat”, ios::out); ofstream outclientFile; outclientFile.open(“clients.dat”, ios::out);

12. 12 Opening Modes for Files ios::app - Write all output to the end of the file ios::ate - Move to the end of the original file when file is opened. Enable data to be written anywhere in the file Table 12- 2 p. 701

13. 13 Opening Modes for Files (Cont’d) ios::in - Open a file for input. ios::out - Open a file for output. ios::trunc - Discard the file’s contents if it exists (this is also the default action for ios::out) Table 12- 2 p. 701

14. 14 Opening Modes for Files (Cont’d) ios::nocreate - If the file does not exist, the open operation fails. ios::noreplace - If the file exists, the open operation fails. ios::binary - Information read or written in pure binary format

15. 15 #include using namespace std; int main() {fstream DataFile; char FileName[81]; cout << “Enter the name of the file you wish to open\n”; cout << “or create:”; cin.getline(FileName); DataFile.open(FileName, ios::out); cout << “The file ” << FileName << ”was opened.\n”; } P. 702 Pgrm. 12-1

16. 16 #include using namespace std; int main() {fstream DataFile; char FileName[81]; cout << “Enter the name of the file you wish to open\n”; cout << “or create:”; cin.getline(FileName); DataFile.open(FileName, ios::out); cout << “The file ” << FileName << ”was opened.\n”; }

17. 17 #include void main(void) {fstream DataFile; DataFile.open(“demofile.txt”, ios::out); if (DataFile == 0) {cout << “File open error!”,, endl; return;} cout << “File opened successfully.\n”; cout << “Now writing information to the file.\n”; DataFile << “Jones\n”; DataFile << “Smith\n”; DataFile <<“Willis\n”; DataFile << “Davis\n”; DataFile.close( ); } P. 702 Pgrm. 12-1

18. 18 Program Screen Output File opened successfully Now writing information to the file. Done. Output to File DEMOFILE.TXT Jones Smith Wilis Davis P. 702

19. 19 J o ne s\n Smit h W il l i s D a v i s P. 702

20. 20 #include int main() {fstream DataFile; DataFile.open(“demofile.txt”, ios::out); DataFile << “Jones\n”; DataFile << “Smith\n”; DataFile.close( ); DataFile.open(“demofile.txt”, ios::app); DataFile << “Willis\n”; DataFile << “Davis\n”; DataFile.close( ); } P. 703 Pgrm. 12-2

21. 21 Output to File DEMOFILE.TXT Jones Smith Wilis Davis Pg. 703

22. 22 J o ne s\n Smit h W il l i s D a v i s P. 704 Fig. 12- 3

23. 23 //This program writes three rows of //numbers to a file. #include # include #include using namespace std; int main () {fstream OutFile(“table.txt, ios::out); int Nums[3] [3] = { 2897, 5, 837, 34, 7, 1623, 390, 3456, 12 }; P. 709 Pgrm. 12-4

24. 24 //Write three rows of numbers for (int Row = 0; row < 3; Row++) { for (int Col = 0; Col < 3; Col++) { OutFile << setw(4)<< Nums[Row] [Col]<<“ ”; } OutFile << endl; } OutFile.close( ); } P. 709 Pgrm. 12-4

25. 25 Contents of File TABLE.TXT 28975837 3471623 390 345612 Pg. 709

26. 26 #include #include using namespace std; bool openFileIn(fstream &, char [51]); void showContents(fstream &); int main() {fstream dataFile; if (!openFileIn(dataFile,”demofile.txt); { cout << “File open error!<< endl; return 0; } P. 710-711 Pgrm. 12-5

27. 27 cout << “File opened successfully.\n”; cout << “Now reading information from the file.\n\n”; showContents(dataFile); cout << “done” ; return 0; // end of main } bool openFileIn(fstream &file, char *name) { bool status; file.open(name,ios::in); if (file.fail()) status = false; else status = true; return status; } P. 711 Pgrm. 12-5

28. 28 void ShowContents(fstream &File) {char Name [81]; while (!File.eof( )){ File >> Name; cout << Name << endl; } P. 711 Pgrm. 12-5

29. 29 J a yn e M u r p h y \n 47 2 J on es Cir c l e \n A l m on d, NC2 8 70 P. 712

30. 30 #include #include using namespace std; int main() {fstream NameFile; char Input[81]; NameFile.open(“murphy.txt”, ios::in); if (NameFile == 0) { cout << “File open error!” << endl; return 0; } nameFile.getline(input,81); while (!NameFile.eof( )) { cout << Input; nameFile.getline(input,81); } NameFile.close( ); } P. 717 Pgrm. 12-8

31. 31 Exercise Write a program that will read all the data in a file and write all the data to a new file removing the blanks. Modify page 730

32. 32 #include #include int main() {fstream inFile; ostream outFile(“out.dat”, ios:: out); char Ch, FileName [51]; cout << “Enter the name of the file”; cin >> FileName; inFile.open(FileName, ios::in); if (!inFile) { cout << FileName << “could not” << “be opened.\n”; return 0;} P. 723-724 Pgrm. 12-12

33. 33 // prime read inFile.get(ch); while (!inFile.eof( )) {if(Ch! = ‘ ‘ ) // change from textbook outFile.put(Ch); inFile.get(Ch); } File.close( ); return 0;} P. 723-724 Pgrm. 12-12

34. 34 Q & A

35. STARTING OUT WITH STARTING OUT WITH Conclusion of Class 15