One of the nice things about Perl is that it comes with a built in manual. Type in the following command: perldoc perlintro and take a look at the section Perl variable types. You can also see this on line with the perldoc.perl.org section on Perl variables. A quick overview: $foo is a scalar variable. … Read more
You had originally tagged this C++, but it would appear to be a C program. C will automatically provide an implicit declaration for a function if there is no prototype in scope (such as due to the omission of #include <stdio.h>). The implicit declaration would be: int printf(); Meaning that printf is a function that … Read more
For Objective-C methods, the general practice is to put methods you wish to expose in the @interface section of the header file so other code can include only the .h and know how to interact with your code. Order-based “lazy declaration” works just like functions in C — you don’t have to declare a method … Read more
As others have pointed out, cdecl is the right tool for the job. If you want to understand that kind of declaration without help from cdecl, try reading from the inside out and right to left Taking one random example from your list char (*(*X[3])())[5]; Start at X, which is the identifier being declared/defined (and … Read more
You can’t separate declaration and definition of lambdas, neither forward declare it. Its type is a unique unnamed closure type which is declared with the lambda expression. But you could do that with std::function objects, which is designed to be able to store any callable target, including lambdas. As your sample code shown you’ve been … Read more
The issue is a little bit subtle; please refer to C++11 3.6.2 for details. What matters for us is that there are two phases of initialization of “non-local variables with static storage duration” (or “global variables” in colloquial parlance): the static initialization phase and the dynamic initialization phase. The static phase comes first. It looks … 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
Add extern to the declaration in the header file. extern int lettersArr[26]; (Also, unless you plan to change the array, consider also adding const.) The definition must have a type. Add int (or const int): int lettersArr[26] = { letA, /*…*/ };
Having tried a simple program (using both 0 and 100, to show the difference between “special” constants and general ones) the Sun Java 6 compiler will output the same bytecode for both 1 and 2 (cases 3 and 4 are identical to 2 as far as the compiler is concerned). So for example: double x … Read more