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# std::basic_ifstream::basic_ifstream

From cppreference.com
< cpp‎ | io‎ | basic ifstream

[edit template]

basic_ifstream(); | (1) |
explicit basic_ifstream( const char* filename, std::ios_base::openmode mode = ios_base::in ); | (2) |
explicit basic_ifstream( const std::filesystem::path::value_type* filename, std::ios_base::openmode mode = ios_base::in ); | (3) | (since C++17)
explicit basic_ifstream( const std::string& filename, std::ios_base::openmode mode = ios_base::in ); | (4) | (since C++11)
explicit basic_ifstream( const std::filesystem::path& filename, std::ios_base::openmode mode = ios_base::in ); | (5) | (since C++17)
basic_ifstream( basic_ifstream&& other ); | (6) | (since C++11)
basic_ifstream( const basic_ifstream& rhs) = delete; | (7) | (since C++11)

Constructs new file stream.

1) Default constructor: constructs a stream that is not associated with a file: default-constructs the std::basic_filebuf and constructs the base with the pointer to this default-constructed std::basic_filebuf member.
2-3) First, performs the same steps as the default constructor, then associates the stream with a file by calling rdbuf()->open(filename, mode | std::ios_base::in) (see std::basic_filebuf::open for the details on the effects of that call). If the open() call returns a null pointer, sets setstate(failbit). Overload (3) is only provided if std::filesystem::path::value_type is not char. (since C++17)
4-5) Same as basic_ifstream(filename.c_str(), mode).
6) Move constructor. First, move-constructs the base class from `other` (which does not affect the `rdbuf()` pointer), then move-constructs the std::basic_filebuf member, then calls this->set_rdbuf() to install the new `basic_filebuf` as the rdbuf() pointer in the base class.
7) The copy-constructor is deleted: this class is not copyable.

### [edit] Parameters

filename | - | the name of the file to be opened
mode | - | specifies stream open mode. It is bitmask type, 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
other | - | another file stream to use as source

### [edit] Example

Run this code

    #include <fstream>
    #include <utility>
    #include <string>
    int main()
    {
        std::ifstream f0;
        std::ifstream f1("test.bin", std::ios::binary);
        std::string name = "example.txt";
        std::ifstream f2(name);
        std::ifstream f3(std::move(f1));
    }

### [edit] See also

open | opens a file and associates it with the stream (public member function) [edit]
open | opens a file and configures it as the associated character sequence (public member function of `std::basic_filebuf`) [edit]
set_rdbuf | replaces the `rdbuf` without clearing its error state (protected member function) [edit]
(constructor) | constructs the object (public member function of `std::basic_istream`) [edit]

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