考慮下面的代碼:差異的行爲愨的libstdC++和的libC++:操作>>對位集
#include <bitset>
#include <sstream>
#include <iostream>
int main(int argc, char* argv[])
{
std::stringstream stream;
std::bitset<1> bitset(1);
std::cout<<"before = "<<bitset[0]<<std::endl;
stream<<"4";
stream>>bitset;
std::cout<<"after = "<<bitset[0]<<std::endl;
return 0;
}
g++
下編譯時libstdc++
,結果是:
> g++ bitset_empty.cpp -o bitset_empty
> ./bitset_empty
before = 1
after = 1
clang++
下編譯時libc++
,結果是:
> clang++ -stdlib=libc++ bitset_empty.cpp -o bitset_empty
> ./bitset_empty
before = 1
after = 0
哪一個是對的?兩者(因爲未定義的行爲?)? GCC?鐺?