std::ios_base::openmode
From cppreference.com
typedef /* implementation defined */ openmode;
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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 ate = /* implementation defined */;
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static constexpr openmode noreplace = /* implementation defined */;
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(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 |
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
See also
| opens a file and configures it as the associated character sequence (public member function of std::basic_filebuf<CharT,Traits>)
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constructs a basic_stringbuf object (public member function of std::basic_stringbuf<CharT,Traits,Allocator>)
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