You must make Foo::comparator static or wrap it in a std::mem_fun class object. This is because lower_bounds() expects the comparer to be a class of object that has a call operator, like a function pointer or a functor object. Also, if you are using C++11 or later, you can also do as dwcanillas suggests and use a lambda function. C++11 also has std::bind too. Examples:
The difference is more prominent when you are passing a big struct/class. when you use use ‘normal’ parameter, you pass the parameter by value and hence creating a copy of the parameter you pass. if you are using const reference, you pass it by reference and the original data is not copied. in both cases, … 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 * == int const * const int * const == int const … 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 * == int const * const int * const == int const … Read more
The difference here is that will place “Hello world” in the read-only parts of the memory, and making s a pointer to that makes any writing operation on this memory illegal. While doing: puts the literal string in read-only memory and copies the string to newly allocated memory on the stack. Thus making legal.
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
That is perfectly acceptable, probably even the standard. where TYPE is the type, NAME is the name in all caps with underscores for spaces, and VALUE is the constant value; I highly recommend NOT putting your constants in their own classes or interfaces. As a side note: Variables that are declared final and are mutable … Read more
A “const function”, denoted with the keyword const after a function declaration, makes it a compiler error for this class function to change a member variable of the class. However, reading of a class variables is okay inside of the function, but writing inside of this function will generate a compiler error. Another way of … Read more
No there is not. You cannot declare a variable or value as constant in Python. Just don’t change it. If you are in a class, the equivalent would be: if not, it is just But you might want to have a look at the code snippet Constants in Python by Alex Martelli. As of Python … Read more