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
Outside of any function, int x; is a tentative definition, and some compilers and linkers treat them as a sort of “cooperative definition,” where an identifier can be declared this way in multiple files and will result in defining only one object. C’s rules for external declarations (declarations outside of functions) are a bit complicated … Read more
Both are legal and both work. But placing [] before the array’s name is recommended. From Javadocs: You can also place the square brackets after the array’s name: float anArrayOfFloats[]; // this form is discouraged However, convention discourages this form; the brackets identify the array type and should appear with the type designation.
C++ (like C) was designed to be implementable by a single-pass compiler. Forward references are necessary in cases where the compiler needs to know that a symbol refers to a class before the class is actually defined. The classic example of this is when two classes need to contain pointers to each other. i.e. class … Read more
For the sake of clarity, I’ll briefly mention terminology. The two arrays are both local variables and arrays of rank 1. alloc_array is an allocatable array; automatic_array is an explicit-shape automatic object. Being local variables their scope is that of the procedure. Automatic arrays and unsaved allocatable arrays come to an end when execution of … Read more
A proper forward declaration is simply: class Level; Note the lack of curly braces. This tells the compiler that there’s a class named Level, but nothing about the contents of it. You can then use pointers (Level *) and references (Level &) to this undefined class freely. Note that you cannot directly instantiate Level since … Read more
Line 11 is p1 = &a; where p1 has type int ** and a has type int[3], right? Well; &a has type int(*)[3] and that type is not compatible with int** as the compiler told you You may want to try p1 = &p0; And read the c-faq, particularly section 6. In short: arrays are … Read more
Both are exactly the same. No difference at all. All that matters is that & should be between the type and the variable name. Spaces don’t matter. So void AddOne(int& y); void AddOne(int &y); void AddOne(int & y) void AddOne(int & y); void AddOne(int&y); are same!
It depends on the scope where you declare the variable. For instance, local variables don’t have default values in which case you will have to assign null manually, where as in case of instance variables assigning null is redundant since instance variables get default values. public class Test { Object propertyObj1; Object propertyObj2 = null; … Read more
The answer depends on what kind of class you’re creating. C++’s compilation model dates back to the days of C, and so its method of importing data from one source file into another is comparatively primitive. The #include directive literally copies the contents of the file you’re including into the source file, then treats the … Read more