std::basic_ospanstream<CharT,Traits>::span
From cppreference.com
< cpp | io | basic ospanstream
std::span<CharT> span() const noexcept; |
(1) | (since C++23) |
void span( std::span<CharT> s ) noexcept; |
(2) | (since C++23) |
1) Gets a
span
referencing the written area if std::ios_base::out is set in the open mode of the wrapped std::basic_spanbuf, or a span
referencing the underlying buffer otherwise.2) Makes the wrapped std::basic_spanbuf perform I/O on the buffer referenced by s.
Contents |
[edit] Parameters
s | - | std::span referencing the storage to be use as the new underlying buffer of stream |
[edit] Return value
1) A std::span referencing the underlying buffer or written area, depending on the open mode of the wrapped std::basic_spanbuf.
2) (none)
[edit] Example
Run this code
#include <cassert> #include <iostream> #include <span> #include <spanstream> int main() { char out_buf[16]; std::ospanstream ost{std::span<char>{out_buf}}; ost << "C++" << ' ' << 23 << '\0'; // note explicit null-termination auto sp = ost.span(); assert( sp[0] == 'C' && sp[1] == '+' && sp[2] == '+' && sp[3] == ' ' && sp[4] == '2' && sp[5] == '3' && sp[6] == '\0' ); std::cout << "sp.data(): [" << sp.data() << "]\n"; std::cout << "out_buf: [" << out_buf << "]\n"; // spanstream uses out_buf as internal storage, no allocations assert(static_cast<char*>(out_buf) == sp.data()); const char in_buf[] = "X Y 42"; std::ispanstream ist{std::span<const char>{in_buf}}; assert(static_cast<const char*>(in_buf) == ist.span().data()); char c; ist >> c; assert(c == 'X'); ist >> c; assert(c == 'Y'); int i; ist >> i; assert(i == 42); ist >> i; // buffer is exhausted assert(!ist); }
Output:
sp.data(): [C++ 23] out_buf: [C++ 23]
[edit] See also
obtains or initializes an underlying buffer according to mode (public member function of std::basic_spanbuf<CharT,Traits> )
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