c++ 文件判空

方法（一）

FILE* fstream = 0;

fstream = fopen(file_name.c_str(), "r");

int worked = (fstream ? 1 : 0);

//if file is empty?
char buf;
int read_count = fread(&buf, 1, 1, fstream);
std::cout<<__FILE__<<__LINE__<<"--read_count--"<<read_count<<std::endl;
if(read_count <= 0)
{
    return false;
}
//seek file to begin if file is not empty
fseek(fstream, 0, SEEK_SET);

方法（二）

// std::file_name = ...

std::ifstream ftmp (file_name.c_str(), std::ios::in);

if (!ftmp.good())
{
    std::cerr << "open file error." << std::endl;
    return true;
}

std::string content;
std::getline( ftmp, content, '\0' );

ftmp.close();

if( d_content.empty() )
{
    std::cout << __FILE__ << __LINE__ << "  file content is empty" << std::endl;
    return true;
}