<ios>
typedefs
ios
Supports the ios
class from the old iostream
library.
typedef basic_ios<char, char_traits<char>> ios;
Remarks
The type is a synonym for class template basic_ios
, specialized for elements of type char
with default character traits.
streamoff
Supports internal operations.
#ifdef _WIN64
typedef __int64 streamoff;
#else
typedef long streamoff;
#endif
Remarks
The type is a signed integer. It describes an object that can store a byte offset in stream positioning operations. Its representation has at least 32 value bits. It isn't necessarily large enough to represent an arbitrary byte position within a stream. The value streamoff(-1)
generally indicates an erroneous offset.
streampos
Holds the current position of the buffer pointer or file pointer.
typedef fpos<mbstate_t> streampos;
Remarks
The type is a synonym for fpos
< mbstate_t
>.
Example
// ios_streampos.cpp
// compile with: /EHsc
#include <iostream>
#include <fstream>
int main( )
{
using namespace std;
ofstream x( "iostream.txt" );
x << "testing";
streampos y = x.tellp( );
cout << streamoff( y ) << '\n';
}
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streamsize
Denotes the size of the stream.
#ifdef _WIN64
typedef __int64 streamsize;
#else
typedef int streamsize;
#endif
Remarks
The type is a signed integer that describes an object that can store a count of the number of elements involved in various stream operations. Its representation has at least 16 bits. It isn't necessarily large enough to represent an arbitrary byte position within a stream.
Example
After compiling and running the following program, look at the file test.txt
to see the effect of setting streamsize
.
// ios_streamsize.cpp
// compile with: /EHsc
#include <iostream>
#include <fstream>
int main( )
{
using namespace std;
char a[16] = "any such text";
ofstream x( "test.txt" );
streamsize y = 6;
x.write( a, y );
}
wios
Supports the wios
class from the old iostream
library.
typedef basic_ios<wchar_t, char_traits<wchar_t>> wios;
Remarks
The type is a synonym for class template basic_ios
, specialized for elements of type wchar_t
with default character traits.
wstreampos
Holds the current position of the buffer pointer or file pointer.
typedef fpos<mbstate_t> wstreampos;
Remarks
The type is a synonym for fpos
< mbstate_t
>.
Example
// ios_wstreampos.cpp
// compile with: /EHsc
#include <iostream>
#include <fstream>
int main( )
{
using namespace std;
wofstream xw( "wiostream.txt" );
xw << L"testing";
wstreampos y = xw.tellp( );
cout << streamoff( y ) << '\n';
}
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