In python, I want a class to have some “constants” (practically, variables) which will be common in all subclasses. Is there a way to do it with friendly syntax? Right now I use: and I’m wondering if there is a better way to do it or a way to do it without then having to … Read more
const_iterators don’t allow you to change the values that they point to, regular iterators do. As with all things in C++, always prefer const, unless there’s a good reason to use regular iterators (i.e. you want to use the fact that they’re not const to change the pointed-to value).
declares ptr a pointer to const int type. You can modify ptr itself but the object pointed to by ptr shall not be modified. While declares ptr a const pointer to int type. You are not allowed to modify ptr but the object pointed to by ptr can be modified. Generally I would prefer the declaration like this which make it easy to read and understand (read from right to left):
The realpath() function gives you the file-system path, with any symbolic links and directory traversing (e.g. ../../) resolved. The dirname() function gives you just the directory, not the file within it. __FILE__ is a magic constant that gives you the filesystem path to the current .php file (the one that __FILE__ is in, not the one it’s included by if it’s an … Read more
There is a misconception here with what const means, probably because it’s a little confusing that this works: but this doesn’t: The issue is that the array size in an array declaration must be a core constant expression. Simplified, that means an expression that’s evaluatable at compile time to be a constant. That is true in the … Read more
Apart from the apparent difference of having to declare the value at the time of a definition for a const VS readonly values can be computed dynamically but need to be assigned before the constructor exits.. after that it is frozen. const‘s are implicitly static. You use a ClassName.ConstantName notation to access them. There is a subtle difference. Consider a class defined … Read more
You don’t need an array of const objects. A pointer-to-const can point to either const or non-const objects; you can create a dynamic array and initialise a Chunk structure from it like this:
Every time I go from heavy C++ coding to Java, it takes me a little while to adapt to the lack of const-correctness in Java. This usage of const in C++ is much different than just declaring constant variables, if you didn’t know. Essentially, it ensures that an object is immutable when accessed through a special kind of pointer … Read more
A: The std::string class has a constructor that takes a char const*, so you simply create an instance to do your conversion. B: Instances of std::string have a c_str() member function that returns a char const* that you can use to convert back to char const*.
char* is a mutable pointer to a mutable character/string. const char* is a mutable pointer to an immutable character/string. You cannot change the contents of the location(s) this pointer points to. Also, compilers are required to give error messages when you try to do so. For the same reason, conversion from const char * to char* is deprecated. char* const is an immutable pointer (it cannot point to any other location) but the contents … Read more