Const usage in C ++ and const usage

Const usage in C ++ and const usage

1 const int a; 2 int const B; // same as 3 // 4 const int * c; // const modifies the data of the memory space d pointed to by the pointer, 5 int * const d cannot be modified;/* d Regular pointer (the pointer variable cannot be modified (d cannot be changed), but the memory space it points to can be modified) */6 const int * const e; // the pointer and the memory space it points to cannot be modified.

The const in C language is not a const in the true sense. in C language, the const variable is a read-only variable and has its own storage space. In C language, the value of a can still be changed by indirect value assignment.

Void main () {// It seems that a is a constant const int a = 10; // a = 11; int * p = NULL; p = (int *) &; * p = 20; // indirect value: printf ("a: % d \ n", a); printf ("* p: % d \ n", * p ); system ("pause ");}

In fact, in C ++, const creates a symbol table. When the pointer is used for indirect value assignment, a memory space will be re-opened. The value of indirect modification of a is only modified, and the value of new memory space will be re-opened, it has nothing to do with the value of a in the original symbol table.

Therefore, const in C ++ is the true const.

Const in C ++ is a real constant instead of a variable (read-only) in C ). It has been determined during the const modified constant compilation.