C + + file offset

1#include <iostream>2#include <fstream>3#include <cassert>4 5 using namespacestd;6 intMain ()7 {8Ifstreaminch("Test_data.txt");9Assertinch. Is_open ());Ten  One     //The base address is at the end of the file with an offset of 0, so the pointer is positioned at the end of the file A     inch. SEEKG (0, ios::end); -     //The SP is a positional pointer because it is at the end of the file, so that is the size of the file -Streampos SP =inch. TELLG ();  thecout<<"File Size:"<<sp<<Endl; -  -     //base Address is the end of the file, the offset address is negative, so move forward Sp/3 bytes -     inch. SEEKG (-sp/3, Ios::end);  +Streampos SP2 =inch. TELLG (); -cout<<"From file to point :"<<sp2<<Endl; +  A     //base Address is the file header, the offset is 0, so locate in the file header; Read the contents of the file from the beginning at     inch. SEEKG (0, Ios::beg); -cout<<inch. RDBUF () <<endl;//All the contents of all output files due to the offset from the beginning -  -     //read the contents of the file from SP2, i.e. everything behind SP2 -     inch. SEEKG (SP2); -cout<<inch. RDBUF () <<Endl; in  -     inch. Close (); to  +     return 0; -}

C + + file offset