Excuse me, why pair, element of the tuple type is not a reference type, but can be a normal class type and pointer types? P1 insert element, what will happen, copy construction string object?

 
Pair P1.//no error 
Pair The p2.//no error 
Pair P3;//error 

CodePudding user response:

Can.

 
int a; 
STD: : pair Ar={a, 1}; 

CodePudding user response:

Want to know what is reference, what are the characteristics of reference and reference can exist independently? Look at the source code, they should be clear