What is std::spanstream (C++23)?

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**std::spanstream** — stream interface over std::span. ```cpp #include // Read from buffer char buffer[] = "Hello World"; std::ispanstream is(buffer); std::string word; is >> word; // "Hello" // Write to buffer char out[100] = {}; std::ospanstream os(out); os << "Value: " << 42; std::cout << out; // "Value: 42" // Read from vector std::vector vec = {'H', 'i', '!', '\0'}; std::ispanstream is2(std::span(vec)); std::string s; is2 >> s; // "Hi!" // Format output char result[50] = {}; std::ospanstream os2(result); os2 << std::hex << 255; std::cout << result; // "ff" // Bidirectional std::spanstream ss(std::span(out)); ss << "New content"; ss.seekg(0); std::string content; ss >> content; ``` **Benefits:** - Parse without string allocation. - Write to fixed-size buffers. - Zero-copy parsing.

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