std::basic_ostream<CharT,Traits>::seekp
From cppreference.com
< cpp | io | basic ostream
basic_ostream& seekp( pos_type pos ); |
(1) | |
basic_ostream& seekp( off_type off, std::ios_base::seekdir dir ); |
(2) | |
Sets the output position indicator of the current associated streambuf
object.
Behaves as UnformattedOutputFunction (except without actually performing output). After constructing and checking the sentry object, |
(since C++11) |
1) if fail() != true, sets the output position indicator to absolute (relative to the beginning of the file) value pos by calling rdbuf()->pubseekpos(pos, std::ios_base::out). In case of failure, calls setstate(std::ios_base::failbit).
2) if fail() != true, sets the output position indicator to offset off relative to dir by calling rdbuf()->pubseekoff(off, dir, std::ios_base::out). In case of failure, calls setstate(std::ios_base::failbit).
Parameters
pos | - | absolute position to set the output position indicator to. | ||||||||
off | - | relative position (positive or negative) to set the output position indicator to. | ||||||||
dir | - | defines base position to apply the relative offset to. It can be one of the following constants:
|
Return value
*this
Exceptions
Example
Run this code
#include <sstream> #include <iostream> int main() { std::ostringstream os("hello, world"); os.seekp(7); os << 'W'; os.seekp(0, std::ios_base::end); os << '!'; os.seekp(0); os << 'H'; std::cout << os.str() << '\n'; }
Output:
Hello, World!
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 129 | C++98 | there was no way to indicate a failure | sets failbit on failure
|
LWG 136 | C++98 | seekp could set the input stream
|
only sets the output stream |
LWG 537 | C++98 | 1. the type of pos was pos_type& 2. the type of off was off_type&
|
1. corrected to pos_type 2. corrected to off_type
|
LWG 2341 | C++98 | the resolution of LWG issue 129 for overload (2) was removed | restored |
See also
returns the output position indicator (public member function) | |
returns the input position indicator (public member function of std::basic_istream<CharT,Traits> ) | |
sets the input position indicator (public member function of std::basic_istream<CharT,Traits> ) |