1. More About File Reading

2. Prompts: Not Needed input.dat 3 -1 34 56 3 14 12 6 124
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file do cout << “What is your next number? ”; } while (fin >> num);
input.dat

3. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file fin >> num; while (num != -1) process_data(num); }
input.dat -1

4. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file fin >> num; while (num != -1) process_data(num); }
input.dat -1

5. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file fin >> num; while (num != -1) process_data(num); }
input.dat -1
marks end
of data

6. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file // SIZE is size of dataset – known a priori for (int i = 0; i < SIZE; i++) fin >> num; process_data(num); }
input.dat

7. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file // size of dataset unknown! while (fin >> num) // returns false when last { // data element read process_data(num); }
input.dat

8. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file while (fin >> num) fin >> num; process_data(num); }
input.dat

9. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file while (fin >> num) fin >> num; //skips every other datum process_data(num); }
input.dat

10. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file while (fin >> num) // gets integer data fin >> name; // gets name data process_data(num, name); }
input.dat
Price
Hurson
Buechler
Davis

11. Reading the Entire File
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ... // code for opening the file fin >> num; // necessary for case of // empty file while (!fin.eof()) process_data(num); fin >> num; }
input.dat
Note: eof becomes true only after trying to read past the last datum

12. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

13. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

14. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

15. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

16. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

17. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

18. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

19. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

20. Example
#include <iostream> #include <fstream> using namespace std; int main() { ifstream in; ofstream out; float next_value; in.open(“input.dat”); out.open(“output.dat”); while (in>>next_value) out<<next_value*next_value<<" "; in.close(); out.close(); return 0; }

21. End of Session