// make_pair example#include 
     
            // std::pair#include 
      
            // std::coutint main () {  std::pair 
       
         foo;  std::pair 
        
          bar;  foo = std::make_pair (10,20);  bar = std::make_pair (10.5,'A'); // ok: implicit conversion from pair
         
            std::cout << "foo: " << foo.first << ", " << foo.second << '\n';  std::cout << "bar: " << bar.first << ", " << bar.second << '\n';  return 0;}
         
        
       
      
     

make_pair

pair.first

pair.second

 

 

----------

Sorting a vector of pairs:

sort(changes.begin(), changes.end(), pairCompare);

在pairCompare函数中定义比较方法：

static bool pairCompare(const pair
     
       pa, const pair
      
        pb){        return pa.first
      
     

 

before sorting 2	10 9	-10 3	15 7	-15 5	12 12 -12 15 10 20 -10 19 8 24 -8 after sorting 2 10 3 15 5 12 7 -15 9 -10 12 -12 15 10 19 8 20 -10 24 -8