1. CS 1430: Programming in C++ 1

2. File Input in VS Project Properties Debugging Command Arguments quiz8-1.out We want to know how to do it ourselves, right? 2

3. Review: Standard Input/Output Stream // Header file #include int size; float avg; cin >> size; // cin: Standard input stream // >>: input operator cout << "Average is " << avg; // cout: standard output stream // <<: output operator 3

4. Header File // Input stream class istream { private: // Members: public: bool eof(); void get(char& x); void getline(char s[], int size, char endChar); … }; istream cin; // Variable of istream // connecting cin to keyboard 4

5. Header File // Output stream class ostream { private: // Members public: bool good(); bool fail(); … }; ostream cout; // Variable of ostream // connecting cout to monitor 5

6. Standard Error Stream cerr << “Error message.”; // cerr: Standard error stream // always go to monitor // Not used yet 6

7. Header File for File I/O // File Stream #include // Input File Stream class ifstream { … }; // Output File Stream class ofstream { … }; 7

8. Class ifstream // File Stream #include class ifstream { private:... public: void open(string fileName); bool good(); bool fail(); void close(); bool eof(); void get(char& x); … }; 8

9. Class ofstream // File Stream #include class ofstream { private:... public: void open(string fileName); void close(); bool good(); bool fail(); … }; 9

10. #include // Defines class ifstream and ofstream int main() { // use any identifiers you want ifstream MyInput; ofstream yourOutFile; ifstream p7_File, cin_redirect; ofstream P6Out, cout_redirect;... return 0; } File Input/Output 10

11. #include int main() { ifstream MyInput; // Open file // void open(string fileName); MyInput.open(“P6.IN"); // P6.IN is in the same folder as the source file MyInput.open(“J:\\P6.IN"); // P6.IN could be any where // Escape char ‘\’ // Do work MyInput.close(); // void close(); // No parameter! return 0; } File Input/Output 11

12. #include int main() { ifstream MyInput; MyInput.open(“P6.IN"); // Check open operation if (!MyInput.good()) cout << "Error: Cannot open input file"; return 0; } Checking Open Operation 12

13. #include int main() { ifstream MyInput; MyInput.open(“P6.IN"); // Check open operation if (MyInput.fail()) { cout << "Error: Cannot open input file"; return 1; } // Do work return 0; } Checking Open Operation 13

14. #include int main() { ifstream MyInput; ofstream yourOutFile; MyInput.open(“P6.IN"); if (MyInput.fail()) { cout << "Error: Cannot open input file!"; return 1; } yourOutFile.open(“p6.out”); if (!yourOutFile.good()) { cout << "Error: Cannot open output file!"; return 1; } … return 0; } File Input/Output 14

15. #include int main() { ifstream MyInput; ofstream yourOutFile; MyInput.open(“P6.IN"); yourOutFile.open(“P6.out”); // Check open file int x; MyInput >> x; // cin >> x; while (!MyInput.eof()) // cin.eof() { // process data x ++; // output to file yourOutFile << x; // cout << x; // read the next value MyInput >> x; } return 0; } File Input/Output 15

16. #include int main() { ifstream MyInput; ofstream yourOutFile; int x; MyInput.open(“P6.IN"); yourOutFile.open(“p6.out”); if (MyInput.fail() || !yourOutFile.good()) { cout << "Error: Cannot open files!"; return 1; } MyInput >> x; while (!MyInput.eof()) { x ++; yourOutFile << x; MyInput >> x; } MyInput.close(); yourOutFile.close(); return 0; } File Input/Output 16

17. // DO_01: Include header file for file I/O int main() { // DO_02: declare variables for file I/O // DO_03: open file // DO_04: Check open operation // DO_05: Read value from a file // DO_06: Fill condition: read until the end of file while ( ) { // DO_07: Output value to a file } // DO_08: Close files } File Input/Output 17

18. int main() { char x; cin.get(x); while(!cin.eof()) { if (x == ' ') // process a space else if (x == '\n') // process a new line char else // process a regular char cin.get(x); } return 0; } // cin >> x will skip all white spaces. // cin.get() will read in white spaces. Function get() 18

19. int main() { char x; ifstream MyInput(“P6.in"); MyInput.get(x); while(!MyInput.eof()) { if (x == ' ') // process a space else if (x == '\n') // process a new line char else // process a regular char MyInput.get(x); } return 0; } // MyInput >> x will skip all white spaces. // MyInput.get() will read in white spaces. Function get() 19

20. int main() { ifstream MyInput; if (!OpenFile(MyInput)) return 1; // Do work return 0; } bool OpenFile(ifstream& inFile) { char file_name[21];// could use C string cin >> file_name; inFile.open(file_name); if (!inFile.good()) { cout << "Error: Cannot open input file"; return false; } else return true; } File Stream as Function Parameter 20

21. Schedule Quiz9–3 10 PM, Wednesday Lab 11 Available on Tuesday Quiz 3 Wednesday, Dec 2 (week 14) 21

22. Schedule Test 3 Wednesday (week 15) Final Exam 7:00-8:52 pm, Tuesday, Dec 15, 2015 Velzy Commons 22

23. Test 3 Classes data members (fields) constructors methods Selection Sorting File I/O Enumeration data type C String (Array of char ) 23