C++ Programming: chapter 6 – iostream

1. C++ Programming: chapter 6 – iostream 2014, Spring Pusan National University Ki-Joune Li http://isel.cs.pnu.edu/~lik

2. // reading a text file #include <iostream> #include <fstream> #include <string> using namespace std; int main () { string line; ifstream myfile ("example.txt”, ); if (myfile.is_open()) { while ( myfile.good() ) { getline (myfile,line); cout << line << endl; } myfile.close(); } else cout << "Unable to open file”; return 0; } fstream, ofstream, ifstream classes

3. ofstream myfile; myfile.open ("example.bin", ios::out | ios::app | ios::binary);

4. #include <iostream> #include <fstream> using namespace std; int main () { long begin,end; ifstream myfile ("example.txt"); begin = myfile.tellg(); myfile.seekg (0, ios::end); end = myfile.tellg(); myfile.close(); cout << "size is: " << (end-begin) << " bytes.\n"; return 0; } ios::beg offset from the beginning ios::cur offset from the current ios::end offset from the end Set Position: tell and seek in C-language

5. // reading a complete binary file #include <iostream> #include <fstream> using namespace std; ifstream::pos_type size; char * memblock; int main () { ifstream file ("example.bin", ios::in | ios::binary | ios::ate); if (file.is_open()) { size = file.tellg(); memblock = new char [size]; file.seekg (0, ios::beg); file.read(memblock, size); file.close(); cout << "the complete file content is in memory"; delete[] memblock; } else cout << "Unable to open file"; return 0; } Binary file i/o stream: read and write in C-Language

6. #include <iostream> using namespace std; int main () { cout.setf(ios::hex, ios::basefield ); // set hex as the basefield cout << 100 << endl; cout.setf(ios::dec, ios::basefield ); // set decimal as the basefield cout.setf(ios::fixed); cout.setf(ios::showpoint); cout.precision(2); cout<<3.141592; cout.set return 0; } cout.width(5); cout << 12.3456 << setw(4) << 12.3456; cout << 12.3456 << setprecision(2) << 12.3456; Set flag: set flags for output stream

7. IOS hierarchy

8. Checking File Status