How to use different ifstream modes in c++?

Question

1. According to the reference, if I use ifstream infile ( "test.txt" , ifstream::in ); it will Allow input operations on the stream. But what are some of the examples of the "input operations"?
2. Is ifstream infile ( "test.txt" , ifstream::in | ifstream::binary ); the right syntax to use multiple flags?
3. Will it make a difference if I change ifstream:: to iso:: ?

Thank you

Answer 1

1. According to the reference, if I use ifstream infile ( "test.txt" , ifstream::in ); it will Allow input operations on the stream. But what are some of the examples of the "input operations"?

Reading from a file which would mean everything an input stream can support. See istream member functions. Typically, you can do both formatted (using >>) and unformatted reads (using read). Remember that ifstream is a specialization of the basic_ifstream template for char type. Depending on your needs, say to read UTF-16 encoded file, you may have to use a different specialization (wifstream) or even use a special locale (read this to know more about locales).

2. Is ifstream infile ( "test.txt" , ifstream::in | ifstream::binary ); the right syntax to use multiple flags?

Yes.

3. Will it make a difference if I change ifstream:: to iso:: ?

No.