c++中ifstream一次讀取整個文件

c++中一次讀取整個文件的內容的方法：

1. 讀取至char*的情況

std::ifstream t;
int length;
t.open("file.txt");      // open input file
t.seekg(0, std::ios::end);    // go to the end
length = t.tellg();           // report location (this is the length)
t.seekg(0, std::ios::beg);    // go back to the beginning
buffer = new char[length];    // allocate memory for a buffer of appropriate dimension
t.read(buffer, length);       // read the whole file into the buffer
t.close();                    // close file handle

// ... do stuff with buffer here ...

2. 讀取至std::string的情況

第一種方法：

#include <string>
#include <fstream>
#include <streambuf>

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

第二種方法：

#include <string>
#include <fstream>
#include <sstream>
std::ifstream t("file.txt");
std::stringstream buffer;
buffer << t.rdbuf();
std::string contents(buffer.str());

reference: http://stackoverflow.com/questions/2602013/read-whole-ascii-file-into-c-stdstring