(C++) std::printf

January 11, 2018 · View on GitHub

 

 

 

 

 

(C++) std::printf

 

std::printf is an STL function to write formatted output to std::cout.

 

std::printf is not typesafe (see example below). For a type-safe alternative, use boost::format instead.

 

 

 

 

 

#include <cstdio> #include <iostream> #include <boost/format.hpp> int main() {   //Correct   std::printf("(x,y) = (%1+5d,%2+5d) \n",-1,2);   std::cout     << boost::format("(x,y) = (%1+5d,%2+5d) \n") % -1 % 2;   //Incorrect   std::printf("(x,y) = (%1+5d,%2+5d) \n",-1.5,2.5);   std::cout     << boost::format("(x,y) = (%1+5d,%2+5d) \n") % -1.5 % 2.5; }

 

Screen output:

 

(x,y) = ( -1, +2) (x,y) = ( -1, +2) (x,y) = ( +0,-1074266112) (x,y) = ( -1.5, +2.5)