Peculiar use of 'const' in C

[cguy]

I've seen this type of code:

In the .c file:


int my_function(const char *const param1, const int param2)
{
...
}


In the header:


int my_function(const char *param1, int param2);


Why is the "const" removed in the header?
It doesn't seem to be a mistake because there are lots of functions declared like this.

[GeneralZod]

The const modifier in "const int param2" is ignored completely when the compiler constructs the function signature (it's 8.3.5.3 in the C++ spec; not sure where in the C one) so that



int my_function(const char *param1, int param2);


and



int my_function(const char *param1, const int param2);


are identical from the compiler's point of view. As to why the const isn't used in the header file: the fact that param2 can't be modified inside the body of my_function is an implementation detail only (which may end up changing) and should be of absolutely no interest to callers of my_function, so it's probably best not to mention it in the header.

Edit:

Note that e.g.



int my_function2(const char *param1);


and



int my_function2(char *param1);


are not the same, however.