std::streamoff

C++

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Technical Specifications

Input/output library

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basic_streambuf

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istrstream (deprecated)

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Synchronized Output

basic_osyncstream (C++20)

Types

streamoff

streamsize

fpos

Error category interface

iostream_category (C++11)

io_errc (C++11)

Defined in header <ios>
typedef /*unspecified*/ streamoff;

The type std::streamoff is a signed integral type of sufficient size to represent the maximum possible file size supported by the operating system. Typically, this is a typedef to long long.

It is used to represent offsets from stream positions (values of type std::fpos). A std::streamoff value of -1 is also used to represent error conditions by some of the I/O library functions.

Relationship with std::fpos

• the difference between two std::fpos objects is a value of type std::streamoff

• a value of type std::streamoff may be added or subtracted from std::fpos yielding a different std::fpos.

• a value of type std::fpos is implicitly convertible to std::streamoff (the conversion result is the offset from the beginning of the file).

• a value of type std::fpos is constructible from a value of type std::streamoff

See also

fpos	represents absolute position in a stream or a file (class template)
seekg	sets the input position indicator (public member function of std::basic_istream)
seekp	sets the output position indicator (public member function of std::basic_ostream)