streampos pubseekpos ( streampos sp, ios_base::openmode which = ios_base::in | ios_base::out );
Set internal position pointer to absolute position
Calls protected virtual member seekpos, which sets a new position value for one or both of the internal position pointers.
The parameter which determines which of the position pointers is affected: either the get pointer gptr or the put pointer pptr, or both.
Parameters
- pos
- New absolute position for the position pointer.
This is an object of class streampos (or traits::pos_type for other traits), which can be constructed directly from integral values representing a relative position from the beginning of the stream.
- which
- Determines which of the internal position pointers shall be modified: the input pointer, the output pointer, or both. It is an object of type ios_base::openmode that for this function may take any combination of the following significant constant values:
| value | position pointer affected |
|---|
| ios_base::in | input position pointer |
| ios_base::out | output position pointer |
Return Value
The new position value of the modified position pointer.
Example
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// changing position with pubseekpos
#include <iostream>
#include <fstream>
using namespace std;
int main () {
int n;
buffer;
filebuf* pbuf;
char buffer[11];
fstream filestr ("test.txt");
pbuf = filestr.rdbuf();
// change position to the 10th character
pbuf->pubseekpos(10);
// read 10 characters
pbuf->sgetn (buffer,10);
// append null character to string
buffer[10]=0;
filestr.close();
cout << buffer << endl;
return 0;
}
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This example reads and prints 10 characters of a file starting at position 10 (characters 10th to 19th).
Basic template member declaration
( basic_streambuf<charT,traits> )
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typedef traits::pos_type pos_type;
pos_type pubseekpos (pos_type sp, ios_base which = ios_base::in | ios_base::out );
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See also
| streambuf::seekpos | Set internal position pointer to absolute position (virtual protected member function) |
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