The reason defining an external variable inside a function does not make sense is the following: When you declare a symbol extern, you are telling the compiler to link all such occurrences of this value into the same symbol. Any occurences of extern int i; in your program would link to the externally defined i. … Read more
Use an initializer list: U_U32_F u = { 0xffffffff }; You can set other members than the first one via U_U32_F u = { .f = 42.0 };
With the first you can use either the type-alias COMPLEX or struct complex. With the second you have an anonymous structure which can only be used with the type-alias COMPLEX. With that said, in C++ any structure name is also a type-name and can be used as a type directly: struct complex { … }; … Read more
The variable scope is the whole batch in this case a stored procedure. It isn’t re-declared every loop So this is exactly as expected Edit: There is a recent blog article which is quite similar. The author was quickly corrected 🙂
It seems like scoping would be the issue, what would be the scope of i declared in the while portion of a do while statement? It would seem rather unnatural to have a variable available within the loop when the declaration is actually below the loop itself. You don’t have this issue with the other … Read more
Only x is a pointer to int; y and z are regular ints. This is one aspect of C declaration syntax that trips some people up. C uses the concept of a declarator, which introduces the name of the thing being declared along with additional type information not provided by the type specifier. In the … Read more
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
No, this is not currently supported. The standard approach is to prefix each field with something unique to the particular datatype, e.g. p2x, p2y, p3x etc. The reason this isn’t supported is that each record field name implicitly generates a “selector” function, e.g. x :: Point2 -> Float. Having two fields with the same name … Read more
Tentative definition is allowed in C but not in C++. A tentative definition is any external data declaration that has no storage class specifier and no initializer. C99 6.9.2/2 A declaration of an identifier for an object that has file scope without an initializer, and without a storage-class specifier or with the storage-class specifier static, … Read more
It’s because const implies internal linkage by default, so your “definition” isn’t visible outside of the translation unit where it appears. In this case, by far the best solution is to put the declaration (extern int const n;) in a header file, and include that in both a.cpp and b.cpp. The linkage is determined by … Read more