lexicographical_compare详解

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lexicographical_compare函数功能:按照字典顺序比较前一区间是否小于后一区间.

template<class _InIt1,

class _InTy,

size_t _InSize,

class _Pr> inline

bool equal(_InIt1 _First1, _InIt1 _Last1,

_InTy (&_First2)[_InSize], _Pr _Pred)

{ // compare [_First1, _Last1) to [First2, ...)

return (_STD equal(_First1, _Last1,

_Array_iterator<_InTy, _InSize>(_First2), _Pred));

}

#endif /* _ITERATOR_DEBUG_LEVEL == 0 */

// TEMPLATE FUNCTION lexicographical_compare

template<class _InIt1,

class _InIt2> inline

bool _Lexicographical_compare(_InIt1 _First1, _InIt1 _Last1,

_InIt2 _First2, _InIt2 _Last2)

{ // order [_First1, _Last1) vs. [First2, Last2)

for (; _First1 != _Last1 && _First2 != _Last2; ++_First1, ++_First2)

if (_DEBUG_LT(*_First1, *_First2))//判断是否*_First1<*_First2

return (true);

else if (*_First2 < *_First1) //*_First1>*_First2

return (false);

//else if *_First2 == *_First

return (_First1 == _Last1 && _First2 != _Last2);

}

另一重载函数不在赘述.

举例:

int main()

{

vector<int> vecInt;

vecInt.push_back( 3 );

vecInt.push_back( 6 );

vecInt.push_back( 5 );

list<int> lstInt;

lstInt.push_back( 3 );

lstInt.push_back( 12 );

lstInt.push_back( 10 );

lstInt.push_back( 6 );

bool bLess = lexicographical_compare(vecInt.begin(),vecInt.end(),lstInt.begin(),lstInt.end() );

system( "pause" );

return 0;

}

需要注意的是,该算法的比较极易出现错误.例如:”111”,”12”.我们认为前者更大,但是实际上是后者更大,原因是长度在此根本不起作用.这类的有string

想要看string更详细的易错问题,请移步至: http://blog.csdn.net/yuanweihuayan/article/details/6641980

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