#include<iostream>
#include<algorithm>
using namespace std;
bool compare(char a,char b)
{
    return a<b;
}
int main()
{
    char a[20]={'a','c','b','e','d'}; int i;
    sort(a,a+5,compare);
    for(i=0;i<5;i++)
        cout<<a[i]<<" ";
    cout<<endl;
    return 0;
}
这是看到有人用sort()函数就研究了下，结构体也自己编了个。就是对结构体里面的2种数据比较成功，比如一个学生姓名和分数的结构体，在名字相同时对分数排名。请大教下，因为是新手，希望大家有代码容易理解，同时对这种排序有其他数据类型的运用，也说明下。

// alg_sort.cpp
// compile with: /EHsc
#include <vector>
#include <algorithm>
#include <functional>      // For greater<int>( )
#include <iostream>

// Return whether first element is greater than the second
bool UDgreater ( int elem1, int elem2 )
{
   return elem1 > elem2;
}

int main( )
{
   using namespace std;
   vector <int> v1;
   vector <int>::iterator Iter1;

   int i;
   for ( i = 0 ; i <= 5 ; i++ )
   {
      v1.push_back( 2 * i );
   }

   int ii;
   for ( ii = 0 ; ii <= 5 ; ii++ )
   {
      v1.push_back( 2 * ii + 1 );
   }

   cout << "Original vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   sort( v1.begin( ), v1.end( ) );
   cout << "Sorted vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   // To sort in descending order. specify binary predicate
   sort( v1.begin( ), v1.end( ), greater<int>( ) );
   cout << "Resorted (greater) vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;

   // A user-defined (UD) binary predicate can also be used
   sort( v1.begin( ), v1.end( ), UDgreater );
   cout << "Resorted (UDgreater) vector v1 = ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")" << endl;
}

sort知识stl里面封装的一个算法
你想知道什么?

他也许是想知道 sort 的第二个参数应该怎么使，或者怎么实现。