Basic meaning and syntax Both keywords can be used in the declaration of objects as well as functions. The basic difference when applied to objects is this: const declares an object as constant. This implies a guarantee that once initialized, the value of that object won’t change, and the compiler can make use of this … Read more
When you add the const keyword to a method the this pointer will essentially become a pointer to const object, and you cannot therefore change any member data. (Unless you use mutable, more on that later). The const keyword is part of the functions signature which means that you can implement two similar methods, one … Read more
If you just want to pass a std::string to a function that needs const char* you can use std::string str; const char * c = str.c_str(); If you want to get a writable copy, like char *, you can do that with this: std::string str; char * writable = new char[str.size() + 1]; std::copy(str.begin(), str.end(), … Read more
You should create a header file like: // Constants.h FOUNDATION_EXPORT NSString *const MyFirstConstant; FOUNDATION_EXPORT NSString *const MySecondConstant; //etc. (You can use extern instead of FOUNDATION_EXPORT if your code will not be used in mixed C/C++ environments or on other platforms.) You can include this file in each file that uses the constants or in the … Read more
Since ES2015, JavaScript has a notion of const: const MY_CONSTANT = “some-value”; This will work in pretty much all browsers except IE 8, 9 and 10. Some may also need strict mode enabled. You can use var with conventions like ALL_CAPS to show that certain values should not be modified if you need to support … Read more
You cannot declare a variable or value as constant in Python. To indicate to programmers that a variable is a constant, one usually writes it in upper case: CONST_NAME = “Name” To raise exceptions when constants are changed, see Constants in Python by Alex Martelli. Note that this is not commonly used in practice. As … Read more
public static readonly fields are a little unusual; public static properties (with only a get) would be more common (perhaps backed by a private static readonly field). const values are burned directly into the call-site; this is double edged: it is useless if the value is fetched at runtime, perhaps from config if you change … 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 … Read more
Read it backwards (as driven by Clockwise/Spiral Rule): int* – pointer to int int const * – pointer to const int int * const – const pointer to int int const * const – const pointer to const int Now the first const can be on either side of the type so: const int * … Read more