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By Sumit Kumar Gupta PGT(CS) KV NO.1, 1st Shift, BBSR.

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Presentation on theme: "By Sumit Kumar Gupta PGT(CS) KV NO.1, 1st Shift, BBSR."— Presentation transcript:

1 By Sumit Kumar Gupta PGT(CS) KV NO.1, 1st Shift, BBSR

2 filebuf : It sets the file buffers to read & write. close( ) & open( ) fstreambase : This is the base class for fstream, ifstream, ofstream classes. open( ) close( ) ifstream : input file stram class. It provide input operation for file. It inherit get( ), getline( ), read( ) and function supporting random access (seekg( ) and tellp( )) from istream class defined inside iostream.h ofstream : Output file stram class. It inherit put( ) and write( ) long with function supporting random access (seekp( ) and tellp( )) from ostream class defined class inside iostream.h fstream : it is an I/O file stream class. It inherits all function from istream and ostream classes through iostream class defined inside iostream.h.

3 Files are required for storing the data and information permanently. 1. Text file : A text file stores information in ASCII characters. Each line terminated by EOL ( end of line). 2. Binary file : It stores information in the same format in which the information is held in memory. No delimiter for line. no translation occurs. It is faster and easier for a program read and write.

4 Using Constructor: ifstream input_file(“DataFile”); char ch; Input_file>>ch; float amt; input_file>>amt; ofstream output_file(“DataFile”); input_file.close( ); output_file.close( );

5 Using Function: ifstream fin; fin.open(“data.dat”); fin.close( );

6 ios::in : open file in read mode, ifstream ios::out : write modeor ios::truncofstream ios::ate : seeks the eof ofstream,ifstream ios::app : appended to the endofstream ios::trunc : open file with zero length ofstream ios::nocreate : not create when open ( ) fail, ofstream ios::noreplace : open( ) fail when file exists, ofstream ios::binary : Open a file in binary mode. By default it is text mode ofstream, ifstream ofstream fout; fout.open(“data.dat”,ios::binary | ios:app); fout.close( );

7 1. Determine the type of link required. 2. Declare a stream for the desired type of link. 3. Attach the desired file to the stream. 4. Now process as required. 5. Close the file-link with stream.

8 1. Determine the type of link required. File to memoryinput Memory to Fileoutput Bothinput/output

9 2.Declare a stream for the desired type of link. File to memoryifstream fin Memory to Fileofstream fout Bothfstream finout

10 3.Attach the desired file to the stream. ifstream fin(“data.dat”); Or fin.open(“data.dat”, ios::in); ofstream fout(“data.dat”); Or fout.open(“data.dat”, ios::out); fstream finout(“data.dat”); Or finout.open(“data.dat”, ios::in | ios::out);

11 4.Now process as required. #include void main( ) {ofstream fout; fout.open(“mark.dat”, ios::out); char ans=‘y’; int rollno; while(ans==‘y’ || ans==‘Y’) { cout<<“\nEnter roll no : “; cin>>rollno; fout<>ans; } fout.close( ); }

12 5. Close the file-link with stream. fin.close( ); fout.close( );

13 #include void main( ) {ofstream fout; fout.open(“mark.dat”,ios::out); int rollno; for(int i=0;i<5;i++) { cout<<“\nEnter roll no : “; cin>>rollno; fout<>rollno; cout<

14 istream & get (char & ch); ostream & put(char ch); int main( ) { char ch; ifstream fin; ifstream fin(“x.dat”, ios::in); if(!fin) { cout<<“Can’t open”; return 1; } while(fin) { fin.get(ch); cout<

15 istream & read((char *) &buf, int sizeof(buf)); ostream & write((char *) &buf, int sizeof(buf)); fin.read((char *) &savec, sizeof(customer)); fout.write((char *) &savec, sizeof(customer));

16 #include struct customer{ char name[51]; float balance;}; void main( ) { customer savac; strcpy(savac.name, “tina”); savac balance= ; ofstream fout; fout.open(“saving”,ios::out | ios::binary); if(!fout) {cout<<“can’t open” ; return 1; } fout.write((char *) &savac, sizeof(customer)); fout.close( ); ifstream fin; fin.open(“saving”,ios::in | ios:: binary); fin.read((char *) &savac, sizeof(customer)); cout<

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