15th Week program Reading-binary and binary files read 3

3, read the following procedure, point out its function, realize the function of SEEKG (), TELLG () function and its usage

(1)

#include <iostream> #include <fstream>using namespace std;const char * filename = "a.txt"; int main () {    Long l,m;    Ifstream file (filename, ios::in|ios::binary);    L = File.tellg ();    FILE.SEEKG (0, ios::end);    m = File.tellg ();    File.close ();    cout << "size of" << filename;    cout << "is" << (m-l) << "bytes.\n";    return 0;}

Operation Result:

(2)

#include <fstream>using namespace Std;int main () {    long pos;    Ofstream outfile;    Outfile.open ("test.txt");    Outfile.write ("This was an apple");    POS=OUTFILE.TELLP ();    OUTFILE.SEEKP (pos-7);    Outfile.write ("Sam", 4);    Outfile.close ();    return 0;}

Operation Result:

(3)

#include <iostream> #include <fstream> using namespace Std;int main () {         fstream outfile,infile;         Outfile.open ("Data.txt", ios::out);         for (int i=0;i<26;i++)       outfile<< (char) (' A ' +i);         Outfile.close ();         Infile.open ("Data.txt", ios::in);         char ch;         INFILE.SEEKG (6,ios::beg);         if (Infile.get (CH))           cout<<ch;         INFILE.SEEKG (8,ios::beg);         if (Infile.get (CH))                 cout<<ch;         INFILE.SEEKG ( -8,ios::end);    if (Infile.get (CH))                 cout<<ch;             cout<<endl;         Infile.close ();     return 0; }

Operation Result:

15th Week program Reading-binary and binary files read 3