The MPL Reference Manual: long_

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# long_

### Synopsis

    template<
          long N
        >
    struct long_
    {
        // unspecified
        // ...
    };

### Description

An Integral Constant wrapper for `long`.

### Header

    #include <boost/mpl/long.hpp>

### Model of

Integral Constant

### Parameters

Parameter | Requirement | Description
--- | --- | ---
`N` | An integral constant | A value to wrap.

### Expression semantics

The semantics of an expression are defined only where they differ from, or are not defined in Integral Constant.

For arbitrary integral constant `n`:

Expression | Semantics
--- | ---
`long_<c>` | An Integral Constant `x` such that `x::value == c` and `x::value_type` is identical to `long`.

### Example

    typedef long_<8> eight;

    BOOST_MPL_ASSERT(( is_same< eight::value_type, long > ));
    BOOST_MPL_ASSERT(( is_same< eight::type, eight > ));
    BOOST_MPL_ASSERT(( is_same< next< eight >::type, long_<9> > ));
    BOOST_MPL_ASSERT(( is_same< prior< eight >::type, long_<7> > ));
    BOOST_MPL_ASSERT_RELATION( (eight::value), ==, 8 );
    assert( eight() == 8 );

### See also

Data Types, Integral Constant, `int_`, `size_t`, `integral_c`