Describes how to interact with a stream.
namespace std {
class ios_base {
public:
typedef implementation-defined-bitmask-type iostate;
static const iostate badbit;
static const iostate eofbit;
static const iostate failbit;
static const iostate goodbit;
...
};
}
Remarks
The type is a bitmask type that describes an object that can store the opening mode for several iostreams objects. The distinct flag values (elements) are:
app, to seek to the end of a stream before each insertion.
ate, to seek to the end of a stream when its controlling object is first created.
binary, to read a file as a binary stream, rather than as a text stream.
in, to permit extraction from a stream.
out, to permit insertion to a stream.
trunc, to delete contents of an existing file when its controlling object is created.
Example
// ios_base_openmode.cpp
// compile with: /EHsc
#include <iostream>
#include <fstream>
int main ( )
{
using namespace std;
fstream file;
file.open( "rm.txt", ios_base::out | ios_base::trunc );
file << "testing";
}
Requirements
Header: <ios>
Namespace: std