I have the following that will open a file for reading. However, I want to check to make sure that the file was open successfully, so I am using the fail to see if the flags have been set. However, I keep getting the following error:
I am new to C++, as I am coming from C. So not sure I understand this error:
cannot call member function ‘bool std::basic_ios<_CharT, _Traits>::fail() const [with _CharT = char, _Traits = std::char_traits]’ without object
Code:
int devices::open_file(std::string _file_name)
{
ifstream input_stream;
input_stream.open(_file_name.c_str(), ios::in);
if(ios::fail() == true) {
return -1;
}
file_name = _file_name;
return 0;
}
You can simply do this:
int devices::open_file(std::string _file_name)
{
ifstream input_stream;
input_stream.open(_file_name.c_str(), ios::in);
if(!input_stream)
{
return -1;
}
file_name = _file_name;
return 0;
}
fail() is not a static method, you must call it on an instance not a type, so if you want to use fail(), replace !input_stream
with input_stream.fail()
in my code above.
I do have to wonder what you're trying to achieve here. You're opening the file and immediately close it again. Are you simply trying to check if the file exists?