遇到 'for_each' is not a member of 'std' 的问题

       今天学Boost库时候用到 标准库的 for_each ， 但是编译总是出错，提示：

        error: 'for_each' is not a member of 'std' 或者  for_each was not declared in this scope

   这是因为缺少头文件 #include <algorithm>，还有不要忘记using namespace std; 或者用std::for_each。

   在http://ubuntuforums.org/showthread.php?t=965086的4楼找到的答案。

顺便提一下for_each用法和boost::bind调用成员函数的优点：

#include <iostream>
#include <boost/bind.hpp>
#include <vector>
#include <algorithm>
class status
{
std::string name_;
bool ok_;
public:
status(const std::string& name):name_(name),ok_(true) {}
void break_it()
{
ok_=false;
}
bool is_broken() const
{
return ok_;
}
void report() const
{
std::cout << name_ << " is " <<
(ok_ ? "working nominally":"terribly broken") << '\n';
}
};
int main(int argc, char** argv)
{
std::vector<status> statuses;
statuses.push_back(status("status 1"));
statuses.push_back(status("status 2"));
statuses.push_back(status("status 3"));
statuses.push_back(status("status 4"));
statuses[1].break_it();
statuses[2].break_it();
std::for_each(
statuses.begin(),
statuses.end(),
/// std::mem_fun_ref(&status::report)
boost::bind(&status::report, _1)
);
return 0;
}

    这样就逐一调用了vector型statuses中每个status类的report成员函数，也许

这和用std::mem_fun_ref没有什么区别，但是当你改用指针时候就不同了，需要用

std::mem_fum而不是mem_fum_ref：

std::vector statuses;
statuses.push_back(new status("status 1"));
statuses.push_back(new status("status 2"));
statuses.push_back(new status("status 3"));
statuses.push_back(new status("status 4"));
statuses[1]->break_it();
statuses[2]->break_it();
std::for_each(
p_statuses.begin(),
p_statuses.end(),
///   std::mem_fun(&status::report)
boost::bind(&status::reprot, _1)
);

    但是如果用boost::bind就不必担心这些了，语法是不变的。

注：代码源自《Beyond the C++ Standard Library: An Introduction to Boost》Library9.