std::streamoff
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header  
<ios>
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|   typedef /*unspecified*/ streamoff; 
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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.
[edit] 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
 
[edit] See also
|    represents absolute position in a stream or a file  (class template)  | 
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|    sets the input position indicator  (public member function of std::basic_istream) 
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|    sets the output position indicator  (public member function of std::basic_ostream) 
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