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

See Also

Concepts

basic_ifstream Class

basic_ifstream Members

iostream Programming

iostreams Conventions