在 C++ 中从 double/int/string 自动转换为 bool

I'm a Java programmer who has been trying to learn a bit of C++ on the side to expand on my knowledge. Here is a small code snippet which I think works due to implicit conversion but I'd like to know which part of the specification does it refer to and what are the other rules which I must be aware of when it comes to implicit conversion. Is there a document/link/site out there which lays down the implicit conversion rules?

#include <vector>
#include <iostream>
#include <iterator>

int main(void) {
  using namespace std;
  vector<bool> a;
  a.push_back("asdf");
  a.push_back("");  
  a.push_back(12);  
  a.push_back(0.0);  
  copy(a.begin(), a.end(), ostream_iterator<bool>(cout, "
"));
  return 0;
}

/*
output:

1
1
1
0
*/

TIA，
佐助

推荐答案

指针和整数以及布尔值都是整数类型.前三个都是指针或整数，因为它们都是非零的，所以它们转换为布尔值 true.double 类型的第四个值转换为零整数值，因此 false.