--- name: "ofdbuf" section: "3bobcat" platform: "linux" package: "libbobcat-dev" version: "6.07.01-2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/ofdbuf" --- # ofdbuf(3bobcat) Output stream buffer initialized by a file descriptor ## NAME FBB::OFdBuf - Output stream buffer initialized by a file descriptor ## SYNOPSIS **#include \**\ Linking option: *-lbobcat* ## DESCRIPTION **FBB::OFdBuf** objects may be used as a *std::streambuf* of *std::ostream* objects to allow insertions into a file descriptor. File descriptors are not defined within the context of **C++**, but they can be used on operating systems that support the concept. Realize that using file descriptors introduces operating system dependencies. ## NAMESPACE **FBB**\ All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace **FBB**. ## INHERITS FROM **std::streambuf** ## ENUMERATION The public enumeration *Mode* defined in the class *FBB::OFdStreamBuf* has the following values: - o **CLOSE\_FD**, indicating that the file descriptor used by the object must be closed; - o **KEEP\_FD** (the default) indicating that the file descriptor used by the object must not be closed. ## CONSTRUCTORS - o **OFdBuf()**:\ This constructor initializes the streambuf, without associating it to a file descriptor, and without using buffering. The member *reset* can be used to associate the object later on with a file descriptor and optionally a buffer size. When the object is destroyed or if the mode-less overloaded version of the *reset* member is called, the file descriptor is closed. - - o **OFdBuf(Mode mode)**:\ This constructor initializes the streambuf, without associating it to a file descriptor, and without using buffering. The member *reset* can be used to associate the object later on with a file descriptor and optionally a buffer size. When the object is destroyed or if the mode-less overloaded version of the member *reset* is called, the *Mode* argument determines whether the file descriptor will be closed or will remain open. - - o **OFdBuf(int fd, size\_t n = 1)**:\ This constructor initializes the streambuf, associating it to file descriptor *fd*, and an optional unget buffer size (by default having size 1). When *reset* is called subsequently, or if the object is destroyed the provided file descriptor will be closed. - - o **OFdBuf(int fd, size\_t n = 1)**:\ This constructor initializes the streambuf, associating it to file descriptor *fd*, and an optional unget buffer size (by default having size 1). When the object is destroyed or if the mode-less overloaded version of the member *reset* is called, the file descriptor will be closed. - - o **OFdBuf(int fd, Mode mode, size\_t n = 1)**:\ This constructor initializes the streambuf, associating it to file descriptor *fd*, and an optional unget buffer size (by default having size 1). When the object is destroyed or if the mode-less overloaded version of the member *reset* is called, the *Mode* argument determines whether the file descriptor will be closed or will remain open. Copy and move constructors (and assignment operators) are not available. ## MEMBER FUNCTIONS All members of *std::streambuf* are available, as *FBB::OFdBuf* inherits from this class. - o **void eoi()**:\ The file descriptor used by the *OFdBuf* is closed, irrespective of the *Mode* that was specified when the *OFdBuf* object was constructed. Following *eoi* the *OFdBuf* object can no longer be used until one of its *reset* members has been called. Instead of using this member the *eoi* manipulator can also be used. - - o **int fd() const**:\ The file descriptor used by the *OFdBuf* object is returned. If the *OFdBuf* is not associated with a file descriptor -1 is returned. - - o **void reset(int xfd, size\_t n = 1)**:\ The streambuf is (re)initialized, using file descriptor *fd*, and an optional unget buffer size (by default having size 1). When called repeatedly, the *Mode* specification used whem the object was constructed determines whether the file descriptor will be closed or will remain open. - - o **void reset(int xfd, Mode mode, size\_t n = 1)**:\ The streambuf is (re)initialized, using file descriptor *fd*, a file descriptor closing parameter and an optional unget buffer size (by default having size 1). Depending on the *Mode* argument the object’s currently used file descriptor will be closed or will remain open when the *IFdBuf* object is destroyed. - - o **void warn(bool on)**:\ When *on == true* a warning is written to the standard error stream when its *sync* member returns -1. If *warn* is not explicitly called *on == true* is used. - ## MANIPULATOR - o **FBB::eoi**:\ The *eoi* manipulator can be inserted into the *ostream* instead of calling the *OFdBuf::end* member. It performs the same actions as the *eoi* member. If inserted into a plain *std::ostream* nothing happens. ## EXAMPLE ``` #include #include #include #include using namespace std; using namespace FBB; int main(int argc, char **argv) { // define a streambuf of 20 or argv[1] characters OFdBuf buf{ STDOUT_FILENO, argc == 1 ? 20 : stoul(argv[1]) }; ostream out{ &buf }; out << "First line, just to start the insertions\n" << argv[0] << endl << // using an explicit flush argc << "\n" "a long line to end this multiple-insertions statement\n"; } ``` ## FILES *bobcat/ofdbuf* - defines the class interface ## SEE ALSO [**bobcat**(7)](/bobcat/7.md), [**ifdbuf**(3bobcat)](/ifdbuf/3bobcat.md), [**ofdstream**(3bobcat)](/ofdstream/3bobcat.md), **std::streambuf** ## BUGS None reported ## BOBCAT PROJECT FILES - o *https://fbb-git.gitlab.io/bobcat/*: gitlab project page; Debian Bobcat project files: - o *libbobcat6*: debian package containing the shared library, changelog and copyright note; - o *libbobcat-dev*: debian package containing the static library, headers, manual pages, and developer info; ## BOBCAT Bobcat is an acronym of \`Brokken’s Own Base Classes And Templates’. ## COPYRIGHT This is free software, distributed under the terms of the GNU General Public License (GPL). ## AUTHOR Frank B. Brokken (**f.b.brokken@rug.nl**).