我对C++还比较新,想要将一个*FILE(例如由popen()返回的)转换为iostream,以便与getline等函数一起使用。我发现了以下代码http://fw-geekycoder.blogspot.co.za/2011/06/how-to-convert-c-file-to-c-iostream.html,以及许多其他类似的代码,但编译器会抱怨boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink> bis(fd);
和boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink> bis(fd);
(Note: The original text contains HTML tags and links. Please keep them in the translation.)
#include <iostream>
#include <cstdio>
#include <unistd.h>
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
void write() {
FILE* fp = fopen("whatever.txt", "w");
if (fp == NULL) {
perror("fopen error");
}
int fd = fileno(fp);
boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink> bis(fd);
std::ostream os(&bis);
os << "Hello World!" << std::endl;
fclose(fp);
}
void read() {
FILE* fp = fopen("whatever.txt", "r");
if (fp == NULL) {
perror("fopen error");
}
int fd = fileno(fp);
boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_source> bis(fd);
std::istream is(&bis);
while (is) {
std::string line;
std::getline(is, line);
std::cout << line << std::endl;
}
fclose(fp);
}
int main() {
write();
read();
return 0;
}
看起来我的系统找到了boost,但好像API或其他东西发生了改变。问题出在哪里?这是我从Eclipse输出的结果:
make all
Building file: ../src/boostPopenHandler.cpp
Invoking: GCC C++ Compiler
g++ -D__GXX_EXPERIMENTAL_CXX0X__ -I../../emdw/src -I../../patrecII/src -I../../ -O0 -g3 -Wall -c -fmessage-length=0 -std=c++0x -MMD -MP -MF"src/boostPopenHandler.d" -MT"src/boostPopenHandler.d" -o"src/boostPopenHandler.o" "../src/boostPopenHandler.cpp"
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = char; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5: required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = char; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:13:83: required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
{ open(detail::path(path), mode); }
^
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:52:5: error: initializing argument 1 of ‘boost::iostreams::detail::path::path(const char*)’ [-fpermissive]
path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
^
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_source::file_descriptor_source(const Path&, std::ios_base::openmode) [with Path = char; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5: required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = char; T = boost::iostreams::file_descriptor_source; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::input_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:26:85: required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:194:36: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
{ open(detail::path(path), mode); }
^
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:52:5: error: initializing argument 1 of ‘boost::iostreams::detail::path::path(const char*)’ [-fpermissive]
path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
^
make: *** [src/boostPopenHandler.o] Error 1
编辑:
根据 Selçuk Cihan 的回答,我已将相关代码更改为:
boost::iostreams::file_descriptor_source fds(fd);
boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_sink>
...
boost::iostreams::file_descriptor_source fds(fd);
boost::iostreams::stream_buffer<boost::iostreams::file_descriptor_source>
但我仍然收到一系列编译错误:
**** Build of configuration Debug for project boostPopenHandler ****
make all
Building file: ../src/boostPopenHandler.cpp
Invoking: GCC C++ Compiler
g++ -I../../emdw/src -I../../patrecII/src -I../../ -O0 -g3 -Wall -c -fmessage-length=0 -std=c++0x -MMD -MP -MF"src/boostPopenHandler.d" -MT"src/boostPopenHandler.d" -o"src/boostPopenHandler.o" "../src/boostPopenHandler.cpp"
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_source::file_descriptor_source(const Path&, std::ios_base::openmode) [with Path = int; std::ios_base::openmode = std::_Ios_Openmode]’:
../src/boostPopenHandler.cpp:13:52: required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:194:36: error: invalid conversion from ‘int’ to ‘const char*’ [-fpermissive]
{ open(detail::path(path), mode); }
^
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:52:5: error: initializing argument 1 of ‘boost::iostreams::detail::path::path(const char*)’ [-fpermissive]
path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
^
In file included from ../src/boostPopenHandler.cpp:4:0:
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5: required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84: required from here
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: error: no matching function for call to ‘boost::iostreams::detail::path::path(const boost::iostreams::file_descriptor_source&)’
{ open(detail::path(path), mode); }
^
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: note: candidates are:
In file included from /usr/include/boost/iostreams/device/file_descriptor.hpp:26:0,
from ../src/boostPopenHandler.cpp:4:
/usr/include/boost/iostreams/detail/path.hpp:138:5: note: boost::iostreams::detail::path::path(const wstring&)
path(const std::wstring&);
^
/usr/include/boost/iostreams/detail/path.hpp:138:5: note: no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const wstring& {aka const std::basic_string<wchar_t>&}’
/usr/include/boost/iostreams/detail/path.hpp:70:5: note: boost::iostreams::detail::path::path(const boost::iostreams::detail::path&)
path(const path& p)
^
/usr/include/boost/iostreams/detail/path.hpp:70:5: note: no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const boost::iostreams::detail::path&’
/usr/include/boost/iostreams/detail/path.hpp:64:14: note: template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::codecvt_type*)
explicit path(const Path& p, typename Path::codecvt_type* = 0)
^
/usr/include/boost/iostreams/detail/path.hpp:64:14: note: template argument deduction/substitution failed:
/usr/include/boost/iostreams/detail/path.hpp: In substitution of ‘template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::codecvt_type*) [with Path = boost::iostreams::file_descriptor_source]’:
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: required from ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’
/usr/include/boost/iostreams/stream_buffer.hpp:94:5: required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84: required from here
/usr/include/boost/iostreams/detail/path.hpp:64:14: error: no type named ‘codecvt_type’ in ‘class boost::iostreams::file_descriptor_source’
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5: required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84: required from here
/usr/include/boost/iostreams/detail/path.hpp:57:14: note: template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::external_string_type*)
explicit path(const Path& p, typename Path::external_string_type* = 0)
^
/usr/include/boost/iostreams/detail/path.hpp:57:14: note: template argument deduction/substitution failed:
/usr/include/boost/iostreams/detail/path.hpp: In substitution of ‘template<class Path> boost::iostreams::detail::path::path(const Path&, typename Path::external_string_type*) [with Path = boost::iostreams::file_descriptor_source]’:
/usr/include/boost/iostreams/device/file_descriptor.hpp:276:36: required from ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’
/usr/include/boost/iostreams/stream_buffer.hpp:94:5: required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84: required from here
/usr/include/boost/iostreams/detail/path.hpp:57:14: error: no type named ‘external_string_type’ in ‘class boost::iostreams::file_descriptor_source’
/usr/include/boost/iostreams/device/file_descriptor.hpp: In instantiation of ‘boost::iostreams::file_descriptor_sink::file_descriptor_sink(const Path&, std::ios_base::openmode) [with Path = boost::iostreams::file_descriptor_source; std::ios_base::openmode = std::_Ios_Openmode]’:
/usr/include/boost/iostreams/stream_buffer.hpp:94:5: required from ‘boost::iostreams::stream_buffer<T, Tr, Alloc, Mode>::stream_buffer(U100&, typename boost::disable_if<boost::is_same<U0, T> >::type*) [with U100 = boost::iostreams::file_descriptor_source; T = boost::iostreams::file_descriptor_sink; Tr = std::char_traits<char>; Alloc = std::allocator<char>; Mode = boost::iostreams::output_seekable; typename boost::disable_if<boost::is_same<U0, T> >::type = void]’
../src/boostPopenHandler.cpp:14:84: required from here
/usr/include/boost/iostreams/detail/path.hpp:52:5: note: boost::iostreams::detail::path::path(const char*)
path(const char* p) : narrow_(p), wide_(), is_wide_(false) { }
^
/usr/include/boost/iostreams/detail/path.hpp:52:5: note: no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const char*’
/usr/include/boost/iostreams/detail/path.hpp:49:5: note: boost::iostreams::detail::path::path(const string&)
path(const std::string& p) : narrow_(p), wide_(), is_wide_(false) { }
^
/usr/include/boost/iostreams/detail/path.hpp:49:5: note: no known conversion for argument 1 from ‘const boost::iostreams::file_descriptor_source’ to ‘const string& {aka const std::basic_string<char>&}’
/usr/include/boost/iostreams/detail/path.hpp:46:5: note: boost::iostreams::detail::path::path()
path() : narrow_(), wide_(), is_wide_(false) { }
^
/usr/include/boost/iostreams/detail/path.hpp:46:5: note: candidate expects 0 arguments, 1 provided
make: *** [src/boostPopenHandler.o] Error 1
boost::iostreams::file_descriptor_source::file_descriptor_source(const Path&, std::ios_base::openmode)
构造函数,即使你提供了一个 int fd。但这就是问题所在。 - Selçuk Cihan