std::basic_stringbuf::seekpos
From cppreference.com
< cpp | io | basic stringbuf
protected:
virtual pos_type seekpos(pos_type sp, |
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Repositions std::basic_streambuf::gptr and/or std::basic_streambuf::pptr, if possible, to the position indicated by sp
Effectively executes seekoff(off_type(sp), std::ios_base::beg, which)
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[edit] Parameters
sp | - | stream position, such as one obtained by seekoff() or seekpos()
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which | - | defines whether the input sequences, the output sequence, or both are affected. It can be one or a combination of the following constants:
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[edit] Return value
sp
on success or pos_type(off_type(-1)) on failure.
[edit] Notes
seekpos()
is called by std::basic_streambuf::pubseekpos(), which is called by the single-argument versions of std::basic_istream::seekg() and std::basic_ostream::seekp()
[edit] Example
Run this code
#include <sstream> #include <iostream> struct mybuf : std::stringbuf { mybuf(const std::string& str) : std::stringbuf(str) {} pos_type seekpos(pos_type sp, std::ios_base::openmode which) { std::cout << "Before seekpos(" << sp << "), size of the get area is " << egptr()-eback() << " with " << egptr()-gptr() << " read positions available\n"; pos_type rc = std::stringbuf::seekpos(sp, which); std::cout << "seekpos() returns " << rc << ".\nAfter the call, " << "size of the get area is " << egptr()-eback() << " with " << egptr()-gptr() << " read positions available\n"; return rc; } }; int main() { mybuf buf("12345"); std::iostream stream(&buf); stream.seekg(2); }
Output:
Before seekpos(2), size of the get area is 5 with 5 read positions available seekpos() returns 2. After the call, size of the get area is 5 with 3 read positions available
[edit] See also
invokes seekpos() (public member function of std::basic_streambuf )
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[virtual]
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repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function) |
[virtual]
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repositions the file position, using absolute addressing (virtual protected member function of std::basic_filebuf )
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[virtual]
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repositions the next pointer in the input sequence, output sequence, or both using absolute addressing (virtual protected member function of std::strstreambuf )
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