std::ios_base::openmode
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ios_base::openmode
typedef /* implementation defined */ openmode;
static constexpr openmode app = /* implementation defined */;
static constexpr openmode binary = /* implementation defined */;
static constexpr openmode in = /* implementation defined */;
static constexpr openmode out = /* implementation defined */;
static constexpr openmode trunc = /* implementation defined */;
static constexpr openmode noreplace = /* implementation defined */;
(since C++23)
Specifies available file open flags. It is a BitmaskType, the following constants are defined:
Constant
Explanation
app
seek to the end of stream before each write
binary
open in binary mode
in
open for reading
out
open for writing
trunc
discard the contents of the stream when opening
ate
seek to the end of stream immediately after open
noreplace (C++23)
open in exclusive mode
[edit] Example
Run this code
#include <fstream> #include <iostream> #include <string> int main() { const char* fname = "unique_name.txt"; // write to a temporary stream object std::fstream (fname, std::ios::out | std::ios::trunc) << "Hi"; std::string s; std::fstream (fname, std::ios::in) >> s; std::cout << s << '\n'; }
Output:
Hi
[edit] See also
opens a file and configures it as the associated character sequence
(public member function of
(public member function of
std::basic_filebuf<CharT,Traits>) [edit]
constructs a
(public member function of
basic_stringbuf object (public member function of
std::basic_stringbuf<CharT,Traits,Allocator>) [edit]