c++ - Const twice in one method parameter? -



c++ - Const twice in one method parameter? -

i'm new c++ , trying understand code i'm looking at:

bool classname::classmethod(const struct_thing* const parametername) {}

what purpose of sec "const" in argument? how differ const struct_thing* parametername?

thanks!

that means const pointer const variable.

see next examples:

int x = 5; // non-const int int* y = &x; // non-const pointer non-const int int const = 3; // const int int* const b = &a; // const pointer non-const int int const* const c = &a; // const pointer const int

so can see 2 things have potential mutable, variable , pointer. either of these 2 can const.

a const variable works you'd imagine:

int foo = 10; foo += 5; // okay! int const bar = 5; bar += 3; // not okay! should result in compiler warning (at least)

a const pointer works same way:

int foo = 10; int bar = 5; int* = &foo; = &bar; // okay! int* const b = &foo; b = &bar; // not okay! should result in compiler warning.

c++

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