std::basic_streambuf<CharT,Traits>::setp
From cppreference.com
protected:
void setp( char_type* pbeg, char_type* pend );
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Sets the values of the pointers defining the put area.
After the call, pbase() == pbeg, pptr() == pbeg and epptr() == pend are all true.
If any of [pbeg, pend) is not a valid range, the behavior is undefined.
Parameters
| pbeg | - | pointer to the new beginning of the put area |
| pend | - | pointer to the new end of the put area |
Example
Run this code
#include <array>
#include <cstddef>
#include <iostream>
// Buffer for std::ostream implemented by std::array
template<std::size_t size, class CharT = char>
struct ArrayedStreamBuffer : std::basic_streambuf<CharT>
{
using Base = std::basic_streambuf<CharT>;
using char_type = typename Base::char_type;
ArrayedStreamBuffer()
{
// put area pointers to work with “buffer”
Base::setp(buffer.data(), buffer.data() + size);
}
void print_buffer()
{
for (char_type i : buffer)
{
if (i == 0)
std::cout << "\\0";
else
std::cout << i;
std::cout << ' ';
}
std::cout << '\n';
}
private:
std::array<char_type, size> buffer{}; // value-initialize “buffer”
};
int main()
{
ArrayedStreamBuffer<10> streambuf;
std::ostream stream(&streambuf);
stream << "hello";
stream << ",";
streambuf.print_buffer();
}
Output:
h e l l o , \0 \0 \0 \0
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 4023 | C++98 | setp did not require the output sequence to be a valid range
|
requires |
See also
| repositions the beginning, next, and end pointers of the input sequence (protected member function) |
