为什么读取不存在的文件会打印垃圾字符？

Question

I try to understand the file reading in c++ and try to read a file that doesn't exist deliberately

//includes ommited

int main(int argc, char ** argv)
{
        if(argc != 1)
                throw std::exception();
        std::ifstream file(argv[0]);
        std::string content((std::istream_iterator<char>(file)), std::istream_iterator<char>());
        std::cout << content.c_str() << std::endl;
}

DEMO

It prints the following:

ELF

Why is it supposed to mean? Do I just get UB by doing this? Since I'm a Java coder I expected that some exception will be thrown if we try to read a file that doesn't exist...

Answer 1

argv[0] contains path to your executable.

http://www.gnu.org/software/libc/manual/html_node/Program-Arguments.html

The file name of the program being run is also included in the vector as the first element; the value of argc counts this element.

Just try to print it's contents:

std::cout << argv[0] << std::endl;

You probably want to use argv[1] .

"ELF" is the begin of file header of Executable and Linkable Format .