Appends the character c to the put area of the buffer, reallocating if possible.
1)If
c == EOF, does nothing.
2) Otherwise, if the put area has a write position available (pptr() < epptr()), stores the character as if by *pptr()++ = c.
3)Otherwise, if the stream buffer mode is not dynamic or the stream buffer is currently frozen, the function fails and returns
EOF.
4)Otherwise, the function reallocates (or initially allocates) a dynamic array large enough to hold the contents of the current dynamic array (if any) plus at least one additional write position. If a pointer to the allocating function
palloc
was used in the constructor, that function is called with
(*palloc)(n)where
n
is the number of bytes to allocate, otherwise
new char[n]is used. If a pointer to the deallocating function
pfree
was used in the constructor, that function is called with
(*pfree)(p)to deallocate the previous array, if needed, otherwise
delete[] pis used. If allocation fails, the function fails and returns
EOF.
[edit] Parameters c - the character to store in the put area [edit] Return valueIf c == EOF, returns some value other than EOF. Otherwise, returns (unsigned char)(c) on success, EOF on failure.
[edit] Example#include <iostream>
#include <strstream>
struct mybuf : std::strstreambuf
{
int_type overflow(int_type c)
{
std::cout << "Before overflow(): size of the put area is " << epptr()-pbase()
<< " with " << epptr()-pptr() << " write positions available\n";
int_type rc = std::strstreambuf::overflow(c);
std::cout << "After overflow(): size of the put area is " << epptr()-pbase()
<< " with " << epptr()-pptr() << " write positions available\n";
return rc;
}
};
int main()
{
mybuf sbuf; // read-write dynamic strstreambuf
std::iostream stream(&sbuf);
stream << "Sufficiently long string to overflow the initial allocation, at least "
<< " on some systems.";
}
Possible output:
Before overflow(): size of the put area is 16 with 0 write positions available After overflow(): size of the put area is 32 with 15 write positions available Before overflow(): size of the put area is 32 with 0 write positions available After overflow(): size of the put area is 64 with 31 write positions available Before overflow(): size of the put area is 64 with 0 write positions available After overflow(): size of the put area is 128 with 63 write positions available[edit] See also writes characters to the associated output sequence from the put area
std::basic_streambuf<CharT,Traits>) [edit] appends a character to the output sequence
std::basic_stringbuf<CharT,Traits,Allocator>) [edit] writes characters to the associated file from the put area
std::basic_filebuf<CharT,Traits>) [edit] writes one character to the put area and advances the next pointer
std::basic_streambuf<CharT,Traits>) [edit] inserts a character
std::basic_ostream<CharT,Traits>) [edit]
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