Get an istream from a char*

Question

I have a char* and the data length that I'm receiving from a library, and I need to pass the data to a function that takes an istream.

I know I can create a stringstream but that will copy all the data. And also, the data will surely have 0s since it's a zip file, and creating a stringstream will take the data until the first 0 I think.

Is there any way to create an istream from a char* and it's size without copying all the data?

Answer 1

Here's a non-deprecated method found on the web, has you derive your own std::streambuf class, but easy and seems to work:

#include <iostream> #include <istream> #include <streambuf> #include <string>  struct membuf : std::streambuf {     membuf(char* begin, char* end) {         this->setg(begin, begin, end);     } };  int main() {     char buffer[] = "I'm a buffer with embedded nulls\0and line\n feeds";      membuf sbuf(buffer, buffer + sizeof(buffer));     std::istream in(&sbuf);     std::string line;     while (std::getline(in, line)) {         std::cout << "line: " << line << "\n";     }     return 0; } 

Which outputs:

line: I'm a buffer with embedded nullsand line line:  feeds