| /*************************************************************************** |
| * |
| * istream1.cpp - istream example |
| * |
| * $Id: //stdlib/dev/examples/stdlib/manual/istream1.cpp#15 $ |
| * |
| *************************************************************************** |
| * |
| * Copyright (c) 1994-2005 Quovadx, Inc., acting through its Rogue Wave |
| * Software division. Licensed under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance with the |
| * License. You may obtain a copy of the License at |
| * http://www.apache.org/licenses/LICENSE-2.0. Unless required by |
| * applicable law or agreed to in writing, software distributed under |
| * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR |
| * CONDITIONS OF ANY KIND, either express or implied. See the License |
| * for the specific language governing permissions and limitations under |
| * the License. |
| * |
| **************************************************************************/ |
| |
| #include <fstream> // for basic_ofstream |
| #include <iostream> // for basic_istream, cout |
| #include <cstdio> // for tmpnam () and remove () |
| |
| #include <examples.h> |
| |
| int main () |
| { |
| #ifndef _RWSTD_STRICT_ANSI |
| |
| // use an extension of this implementation: NULL file name argument |
| // creates a temporary file; closing the file stream object or its |
| // associated filebuf removes the temporary file |
| const char* const fname = 0; |
| |
| #else // if defined (_RWSTD_STRICT_ANSI) |
| |
| char fnamebuf [L_tmpnam]; |
| |
| // create a temporary filename |
| const char* const fname = std::tmpnam (fnamebuf); |
| |
| if (!fname) |
| return 1; |
| |
| #endif // _RWSTD_STRICT_ANSI |
| |
| // typedefs for convenience |
| typedef std::basic_istream<char, std::char_traits<char> > Input; |
| typedef std::basic_ofstream<Input::char_type, Input::traits_type> Output; |
| |
| Input::char_type s [200]; |
| |
| // open a file for read and write operations |
| Output out (fname, std::ios::in | std::ios::out | std::ios::trunc); |
| |
| // tie the istream object to the ofstream filebuf |
| Input in (out.rdbuf ()); |
| |
| double x = 3.14159; |
| int i = 3; |
| |
| // output to the file |
| out << "He lifted his head and pondered.\n" |
| << x << '\n' << i << '\n'; |
| |
| // seek to the beginning of the file |
| in.seekg (0); |
| |
| // read from the file using formatted functions |
| in.getline (s, sizeof s); |
| in >> x >> i; |
| |
| // seek to the beginning of the file |
| in.seekg (0, std::ios::beg); |
| |
| // output the all file to the standard output |
| std::cout << in.rdbuf (); |
| |
| // seek to the beginning of the file |
| in.seekg (0); |
| |
| // read the first line in the file |
| // "He lifted his head and pondered." |
| in.getline (s, sizeof s / 2); |
| |
| std::cout << s << '\n'; |
| |
| // read the second line in the file |
| in.getline (s, sizeof s / 2); |
| |
| std::cout << s << '\n'; |
| |
| // seek to the beginning of the file |
| in.seekg (0); |
| |
| // read the first line in the file |
| // "He lifted his head and pondered." |
| in.get (s, sizeof s / 2); |
| |
| // remove the newline character |
| in.ignore (); |
| |
| std::cout << s << '\n'; |
| |
| // read the second line in the file |
| // 3.14159 |
| in.get (s, sizeof s / 2); |
| |
| std::cout << s << '\n'; |
| |
| // remove the newline character |
| in.ignore (); |
| |
| // store the current file position |
| const Input::pos_type position = in.tellg (); |
| |
| out << "\nreplace the int\n"; |
| |
| // move back to the previous saved position |
| in.seekg (position); |
| |
| // for convenience |
| const Input::int_type eof = Input::traits_type::eof (); |
| |
| // output the remainder of the file |
| // this is equivalent to "std::cout << in.rdbuf ();" |
| while (!Input::traits_type::eq_int_type (in.peek (), eof)) |
| std::cout << Input::traits_type::to_char_type (in.get ()); |
| |
| std::cout << "\n\n\n"; |
| |
| if (fname) { |
| // close the stream before removing the file |
| out.close (); |
| |
| // remove the temporary file (must have a name) |
| std::remove (fname); |
| } |
| |
| return 0; |
| } |