lexicographical_compare：

C++ STL 泛型算法函数：用于按字典序比较两个序列。

函数申明：

//重载1，如果[first1, last1)按字典序列小于[first2, last2)，返回true，否则返回false。

template <class InputIterator1, class InputIterator2 >

bool

lexicographical_compare(

InputIterator1 first1, InputIterator1 last1,

InputIterator2 first2, InputIterator2 last2 );

//重载2，功能同重载1，增加了比较函数comp，即大小关系由comp函数确定。

template < class InputIterator1, class InputIterator2,

class Compare >

bool

lexicographical_compare(

InputIterator1 first1, InputIterator1 last1,

InputIterator2 first2, InputIterator2 last2,

Compare comp );

示例代码：

#include <algorithm>

#include <iostream>

#include <iterator>

using namespace std;

void Output(const int * a,const int & a_size,const int * b,const int & b_size)

{

cout<<"a[]=";

copy(a,a+a_size,ostream_iterator<int>(cout," "));

cout<<endl;

cout<<"b[]=";

copy(b,b+b_size,ostream_iterator<int>(cout," "));

cout<<endl;

}

typedef bool (* CMP)(const int &,const int &);

int Compare(const int * a,const int & a_size,const int * b,const int & b_size,CMP cmp) //按照cmp方式进行比较

{

bool ASmallerThanB,BSmallerThanA;

ASmallerThanB=lexicographical_compare(a,a+a_size,b,b+b_size,cmp); //按照cmp方式进行比较

BSmallerThanA=lexicographical_compare(b,b+b_size,a,a+a_size,cmp);

if(! ASmallerThanB && ! BSmallerThanA) //a[] 和 b[] 相等

return 0;

else if(ASmallerThanB) //a[] < b[]

return -1;

else

return 1;

}

int Compare(const int * a,const int & a_size,const int * b,const int & b_size) //默认比较方式

{

bool ASmallerThanB,BSmallerThanA;

ASmallerThanB=lexicographical_compare(a,a+a_size,b,b+b_size); //默认比较方式

BSmallerThanA=lexicographical_compare(b,b+b_size,a,a+a_size);

if(! ASmallerThanB && ! BSmallerThanA) //a[] 和 b[] 相等

return 0;

else if(ASmallerThanB) //a[] < b[]

return -1;

else

return 1;

}

bool greater(const int & a,const int & b) //自定义越大的字典序越小

{

return a>b;

}

int main()

{

int a[]={1,2,3,4,5,6};

int b[]={1,2,3,4,5,6};

Output(a,6,b,6);

cout<<"Compare(a,6,b,6)="<<Compare(a,6,b,6)<<endl;

cout<<"Compare(a,6,b,6,greater)="<<Compare(a,6,b,6,greater)<<endl;

rotate(a+2,a+4,a+6);

Output(a,6,b,6);

cout<<"Compare(a,6,b,6)="<<Compare(a,6,b,6)<<endl;

cout<<"Compare(a,6,b,6,greater)="<<Compare(a,6,b,6,greater)<<endl;

return 0;

}

return a>b;

}

int main()

{

int a[]={1,2,3,4,5,6};

int b[]={1,2,3,4,5,6};

Output(a,6,b,6);

cout<<"Compare(a,6,b,6)="<<Compare(a,6,b,6)<<endl;

cout<<"Compare(a,6,b,6,greater)="<<Compare(a,6,b,6,greater)<<endl;

rotate(a+2,a+4,a+6);

Output(a,6,b,6);

cout<<"Compare(a,6,b,6)="<<Compare(a,6,b,6)<<endl;

cout<<"Compare(a,6,b,6,greater)="<<Compare(a,6,b,6,greater)<<endl;

return 0;

}