第十五周阅读项目3.（1）

#include<iostream>
#include <fstream>
using namespace std;
const char * filename = "a.txt";
int main ()
{
    long l,m;
    ifstream file (filename, ios::in|ios::binary);
    l = file.tellg();
    file.seekg (0, ios::end);
    m = file.tellg();
    file.close();
    cout << "size of " << filename;
    cout << " is " << (m-l) << " bytes.\n";
    return 0;
}