limingjie / all_to_istream

Process standard input, file or string as istream.

#All to istream This is a dummy demo on how to process standard input, file or string as istream.

##Why istream It is common to interpret string, file or standard input (especially redirected) character by character. To process them in a single function is very convenient, which saves programmer some effort and provides a more user friendly interface.

Input stream can interpret input from sequences of characters. Useful functions are provided or inherited from ios or ios_base.

std::istream reference

##How to convert different inputs to istream

• Standard input stream

  std::cin is defined as istream

  extern istream cin;

• std::fstream and std::stringstream

  Both fstream and stringstream are inherited from iostream, which inherited from istream.

  ios_base <--- ios <--- istream <--- iostream <--- fstream
                                               <--- stringstream
  

• std::string

  string can be converted to stringstream.

  explicit stringstream (const string& str,
                         ios_base::openmode which = ios_base::in | ios_base::out);

##Usage

$ ./all_to_istream -h
Usage: all_to_istream
   or: all_to_istream FILE
   or: all_to_istream -s STRING
   or: all_to_istream -h
Process standard input, file or string as istream, to simplify support to different inputs.

$ ./all_to_istream
Info: read_std_input
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod.
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod.
^D

$ ./all_to_istream > lorem.txt
Info: read_std_input
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod.
^D

$ ./all_to_istream < lorem.txt
Info: read_std_input
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod.

$ cat lorem.txt | ./all_to_istream
Info: read_std_input
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod.

$ ./all_to_istream lorem.txt
Info: read_file
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod.

$ ./all_to_istream -s "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod."
Info: read_string
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod.
$ ./all_to_istream.exe lorem
Error: fail to open file lorem