本博客转载自:http://blog.csdn.net/sayesan/article/details/45840337.
1 调用ifstream打开一个文件
2 调用seekg将get pointer置为文件末尾,seekg(0, ios_base::end)
3 调用tellg获取总字节数,实际上获取的是get pointer相对于文件头的偏移字节数
4 重置get pointer,使其指向文件头,以便执行其他操作
以下代码摘自www.cplusplus.com
#include <iostream>
#include <fstream>
using namespace std;
int main () {
int length;
char * buffer;
ifstream is;
is.open ("test.txt", ios::binary );
// get length of file:
is.seekg (0, ios::end);
length = is.tellg();
is.seekg (0, ios::beg);
// allocate memory:
buffer = new char [length];
// read data as a block:
is.read (buffer,length);
is.close();
cout.write (buffer,length);
return 0;
}
对于ifstream对象的每一次read过后,可以调用ifstream::gcount获取读取的字节数,
gcount的返回值为streamsize,而streamsize是个整型,signed int或signed long