ifstream.read() does not read anything?

I got some file-reading problems in my project, so I wrote following test codes.

I'm tring to read a file by ifstream.read()，but anything has been read.

I've searched numerous related questions, but still can't figure out why my code doesn't work. please help.

#include <iostream>
#include <fstream>

int main() {
    /*--------------- write file ----------------*/
    std::ofstream ofs("testfile", std::ios::binary);
    const char *content = "11223344";
    ofs.write(content, sizeof content);

    system("chmod 777 testfile");

    /*--------------- read file ----------------*/

    char arr[8] = {0};
    const int length = sizeof arr / sizeof arr[0];
    std::ifstream ifs("testfile", std::ios::binary);

    std::cout << "good: " << ifs.good() << std::endl;  // 1

    ifs.seekg(0, ifs.end);
    int file_size = ifs.tellg();
    ifs.seekg(0, ifs.beg);
    std::cout << "file_size: " << file_size << std::endl << std::endl;  // 0

    if (ifs) {
        ifs.read(&arr[0], 2);
        std::cout << "after read," << std::endl;
        std::cout << "gcount: " << ifs.gcount() << std::endl;  // 0
        std::cout << "good: " << ifs.good() << std::endl;  // 0
        ifs.read(&arr[2], 2);
        ifs.read(&arr[4], 2);
        ifs.read(&arr[6], 2);
    } else {
        std::cout << "file not found" << std::endl;
    }

    for (int i = 0; i < length; ++i) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

The output is

good: 1
file_size: 0

after read,
gcount: 0
good: 0
0 0 0 0 0 0 0 0