basic_ifstream::basic_ifstream
Constructs an object of type basic_ifstream.
basic_ifstream( );
explicit basic_ifstream(
const char *_Filename,
ios_base::openmode _Mode = ios_base::in,
int _Prot = (int)ios_base::_Openprot
);
explicit basic_ifstream(
const wchar_t *_Filename,
ios_base::openmode _Mode = ios_base::in,
int _Prot = (int)ios_base::_Openprot
);
Parameters
_Filename
The name of the file to open._Mode
One of the enumerations in ios_base::openmode._Prot
The default file opening protection.
Remarks
The first constructor initializes the base class by calling basic_istream(sb), where sb is the stored object of class basic_filebuf<Elem, Tr>. It also initializes sb by calling basic_filebuf<Elem, Tr>.
The second and third constructors initializes the base class by calling basic_istream(sb). It also initializes sb by calling basic_filebuf<Elem, Tr>, then sb.open(_Filename, _Mode | ios_base::in). If the latter function returns a null pointer, the constructor calls setstate(failbit).
Example
The following example shows how to read in text from a file. To create the file, see the example for basic_ofstream::basic_ofstream.
// basic_ifstream_ctor.cpp
// compile with: /EHsc
#include <fstream>
#include <iostream>
using namespace std;
int main(int argc, char **argv)
{
ifstream ifs("basic_ifstream_ctor.txt");
if (!ifs.bad())
{
// Dump the contents of the file to cout.
cout << ifs.rdbuf();
ifs.close();
}
}
Input: basic_ifstream_ctor.txt
This is the contents of basic_ifstream_ctor.txt.
Output
This is the contents of basic_ifstream_ctor.txt.
Requirements
Header: <fstream>
Namespace: std