#include  
#include  
using namespace std; 

Int main () 
{
Priority_queue & lt; Int> Q; 
For (int I=0; I & lt; 5; I++) 
Q.p ush (I); 

while(! Q.e mpty ()) 
{
Const int& Cur=q.t op (); Q.p op (); 
STD: : cout & lt; } 

return 0; 
} 

The above code print result: 3 2 1 0 0
If the const int& Cur=q.t op (); Modified to const int cur=q.t op (); Printing result is 4 3 2 1 0, normal,
Why have a problem with reference to receive?

CodePudding user response:

Because reference itself, namely cur=top when pop, cur pointing to his top now, so change
And the value of cur=top () is to replicate, pop, cur constant

CodePudding user response:

1/f, positive solutions, you this API design not good, can you guarantee you top no illegal operation? STD: : must judge is not empty to front (), don't pop_front. The meaning and you 2 above, if the empty cut in front can produce unpredictable errors,