How simplicity read text file,which contain one or three values?

[AKE]

Text file can conain one or three integer values in string. How correctly and simplicity read this string?

[VictorN]

If the file is the text one then read it as text, then parse this text to get what you need.
If MFC project you could use CStdioFile class to read a file, and CString class to parse.