std::string formatting like sprintf

Question

I have to format std::string with sprintf and send it into file stream. How can I do this?

Answer 1

boost::format() provides the functionality you want:

As from the Boost format libraries synopsis:

A format object is constructed from a format-string, and is then given arguments through repeated calls to operator%. Each of those arguments are then converted to strings, who are in turn combined into one string, according to the format-string.

#include 

cout << boost::format("writing %1%,  x=%2% : %3%-th try") % "toto" % 40.23 % 50; 
// prints "writing toto,  x=40.230 : 50-th try"