More About File Reading.

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Ross Bryant
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1 More About File Reading

2 Prompts: Not Needed #include <string>... // code for opening the file input.dat do cout << What is your next number? ; while (fin >> num);

3 Reading the Entire File #include <string>... // code for opening the file input.dat fin >> num; while (num!= -1) process_data(num); fin >> num;

4 Reading the Entire File #include <string>... // code for opening the file input.dat fin >> num; while (num!= -1) process_data(num); fin >> num;

5 Reading the Entire File #include <string>... // code for opening the file fin >> num; marks end of data input.dat while (num!= -1) process_data(num); fin >> num;

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

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

8 Reading the Entire File #include <string>... // code for opening the file input.dat while (fin >> num) fin >> num; process_data(num);

9 Reading the Entire File #include <string>... // code for opening the file input.dat while (fin >> num) fin >> num; //skips every other datum process_data(num);

10 Reading the Entire File #include <string>... // code for opening the file input.dat Price Hurson Buechler Davis while (fin >> num) // gets integer data fin >> name; // gets name data process_data(num, name);

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

12 Example 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 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 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 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 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 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 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 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 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

Class 14. Input File Streams. Laura Marik Spring 2012 C++ Course Notes (Provided by Jason Minski)

Class 14. Input File Streams. Laura Marik Spring 2012 C++ Course Notes (Provided by Jason Minski) Class 14 Input File Streams A program that reads 10 integers from a file int main() { string filename; // the name of the file to be opened ifstream fin; // the input file stream int array[10]; // an array