basic_istream::seekg
Moves the read position in a stream.
basic_istream<Elem, Tr>& seekg(
pos_type pos
);
basic_istream<Elem, Tr>& seekg(
off_type off,
ios_base::seekdir way
);
Parameters
pos
The absolute position in which to move the read pointer.off
An offset to move the read pointer relative to way.way
One of the ios_base::seekdir enumerations.
Return Value
The stream (*this).
Remarks
The first member function performs an absolute seek, the second member function performs a relative seek.
Note
Do not use the second member function with text files, because Standard C++ does not support relative seeks in text files.
If fail is false, the first member function calls newpos = rdbuf -> pubseekpos(pos), for some pos_type temporary object newpos. If fail is false, the second function calls newpos = rdbuf -> pubseekoff(off, way). In either case, if (off_type)newpos == (off_type)(-1) (the positioning operation fails), the function calls istr.setstate(failbit). Both functions return *this.
If fail is true, the member functions do nothing.
Example
// basic_istream_seekg.cpp
// compile with: /EHsc
#include <iostream>
#include <fstream>
int main ( )
{
using namespace std;
ifstream file;
char c, c1;
file.open( "basic_istream_seekg.txt" );
file.seekg(2); // seek to position 2
file >> c;
cout << c << endl;
}
Input: basic_istream_seekg.txt
0123456789
Output
2
Requirements
Header: <istream>
Namespace: std