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What is the most elegant way to write a text / binary using C ++?

I found good reading results, for example: Read txt with iterators and preallocation or read in containers . So I wondered how to write the most elegant std :: string to a file?

Edit: when reading, I can pre-allocate space for the line using seek and tellg, since I know the size of the line, how can I tell the file system how much I want to write?

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3 answers

Here is a tiny example of how to output std::string, but you really need to read fstream

#include <iostream>
#include <fstream>
#include <string>

int main(int argc, char *argv[])
{

  std::string s("writemeout");
  std::ofstream outfile("output.txt");
  if(!outfile.is_open()) {
    std::cerr << "Couldn't open 'output.txt'" << std::endl;
    return -1;
  }

  outfile << s << std::endl;
  outfile.close();
  return 0;
}
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operator<< std::ofstream. :

#include <fstream>
#include <string>

int main() {
    std::string s( "Hello, World!" );
    std::ofstream f( "hello.txt" );
    if ( !f.fail() )
        f << s;
}
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, .

std::ofstream ofs; // presumed open
ofs << v1 << v2 << v3 << v4 << v5; // some different variables
ofs.close();

std::ifsteram ifs; // open to same stream
ifs >> r1 >> r2 >> r3 >> r4 >> r5; // variables of same types as above

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