C++ 中使用 fstream 一次读取整个文件内容

原文地址 https://www.cnblogs.com/kex1n/p/4028428.html

读取到 char*

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 ...

读取到 std::string

方法一

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

方法二

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