c++中ifstream一次读取整个文件

#include <string>  
#include <fstream>  
#include <streambuf>  
  
std::ifstream t("file.txt");  
std::string str((std::istreambuf_iterator<char>(t)),  
                 std::istreambuf_iterator<char>());

#include <string>  
#include <fstream>  
#include <sstream>  

std::ifstream t("file.txt");  
std::stringstream buffer;  
buffer << t.rdbuf();  
std::string contents(buffer.str());