Hello Tom, -----Original Message----- From: tom gee [mailto:rockonedge@gmail.com] Subject: [Boost-users] A question about boost::lambda::if_ behavior
Can anyone please explain this code: [snip]
The problem is that the expression std::cout << constant("Bingo:<") is evaluated immediately. Why? Because it's not a lambda expression. You have two options that will help you turn your if-branch into a lambda expression; either use boost::lambda::var or boost::lambda::constant. Using boost::lambda::var: std::for_each(setFinalVal.begin(),setFinalVal.end(), (std::cout << _1 << " ", if_(_1 < 24.000001 && _1 > 23.999999) [var(std::cout) << "Bingo:<" << _1 << ">"])); Using boost::lambda::constant: std::for_each(setFinalVal.begin(),setFinalVal.end(), (std::cout << _1 << " ", if_(_1 < 24.000001 && _1 > 23.999999) [std::cout << constant("Bingo:<") << _1 << ">"])); Cheers, Bjorn Karlsson