++ I vs I ++

[Analysis]

Which of the following is the higher I ++ and I efficiency?

(1) There is no difference in efficiency in the case of internal data types;

(2) In the case of custom data type class, ++ is more efficient!

When the user-defined data type is used: ++ I returns an object reference; I ++ always creates a temporary object and destroys it when exiting the function, in addition, the copy constructor is also called when the temporary object value is returned.

[Code]

C ++ code

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# Include <stdio. h> # Include <stdlib. h> # Include <string. h> # Include <vector> # Include <iostream> Using namespace STD; Class integer { Public: INTEGER (INT value): V (value) { Cout <"default constructor" <Endl; } INTEGER (const integer & other) { Cout <"copy constructor" <Endl; V = Other. V; } Integer & operator = (const integer & other) { Cout <"Copy assignment" <Endl; V = Other. V; Return * this; } // ++ I first + 1, then return New Value Integer & operator ++ () { Cout <"INTEGER: Operator ++ ()" <Endl; V ++; Return * this; } // I ++ first save old value, then + 1, last return old value Integer operator ++ (INT) { Cout <"INTEGER: Operator ++ (INT)" <Endl; Integer old = * this; V ++; Return old; } Void output () { Cout <"value" <v <Endl; } PRIVATE: Int V; }; Void test_case () { Integer OBJ (10 ); Integer obj2 = OBJ; Integer obj3 (0 ); Obj3 = OBJ; Cout <"--------------" <Endl; Cout <"++ I" <Endl; ++ OBJ; OBJ. Output (); Cout <"I ++" <Endl; OBJ ++; OBJ. Output (); } Int main () { Test_case (); Return 0; } /* Default constructor Copy constructor Default constructor Copy assignment -------------- ++ I Integer: Operator ++ () Value 11 I ++ Integer: Operator ++ (INT) Copy constructor Value 12 */

++ I vs I ++