There's another error here:

The qualifier const can be added to the left of a variable or parameter type

If you have the declaration

  char* str;

Adding const to the left of the type doesn't make the variable immutable:

  const char* str;

This indicates that str will point to a character or string which must not be mutated. str itself can be reassigned. To make str immutable, you need

  char* const str; // immutable pointer to mutable string

or

  const char* const str; // immutable pointer to immutable string

Const does tend to be used little in pure C, though you pretty much can't escape it in C++ code. (I also use it a lot in C, and have type warnings/errors cranked up to max)