The typedef would be However, this is probably a very bad idea, because the resulting type is an array type, but users of it won’t see that it’s an array type. If used as a function argument, it will be passed by reference, not by value, and the sizeof for it will then be wrong. A better … Read more
It has nothing to do with your typedef. The problem is that you haven’t given a return type for main: A function must have a return type. The main function must return int.
You cannot use pEDGE within the definition of the struct. You shoud do something like: You must also note that edge_item is a double pointer. You also mention that in your question. So if you use pEDGE_ITEM and you just want to have a normal pointer you should not write pEDGE_ITEM *edge_item but just pEDGE_ITEM … Read more
No, there’s no true equivalent of typedef. You can use ‘using’ directives within one file, e.g. but that will only impact that source file. In C and C++, my experience is that typedef is usually used within .h files which are included widely – so a single typedef can be used over a whole project. … Read more
In C, declaring your enum the first way allows you to use it like so: If you use the second style, you’ll be forced to declare your variable like this: As mentioned by others, this doesn’t make a difference in C++. My guess is that either the person who wrote this is a C programmer … Read more
In C++, there is only a subtle difference. It’s a holdover from C, in which it makes a difference. The C language standard (C89 §3.1.2.3, C99 §6.2.3, and C11 §6.2.3) mandates separate namespaces for different categories of identifiers, including tag identifiers (for struct/union/enum) and ordinary identifiers (for typedef and other identifiers). If you just said: … Read more
typedef is a language construct that associates a name to a type.You use it the same way you would use the original type, for instance using them like As you can see, you could just replace the typedefed name with its definition given above. The difficulty lies in the pointer to functions syntax and readability … Read more
so your answer is But naturally, this is a bad practice, just use typedefs 🙂 Extra: Wonder how to declare an array of 3 pointers to functions taking int and returning a pointer to an array of 4 pointers to functions taking double and returning char? (how cool is that, huh? :)) :))
I saw a question the other day where someone inadvertently used an incomplete type by specifying something like The compiler knew that struct A was a struct, despite A being totally undefined, by virtue of the struct keyword. That was in C++, where such usage of struct is atypical (and, it turns out, can lead … Read more
The common idiom is using both: They are different definitions. To make the discussion clearer I will split the sentence: In the first line you are defining the identifier S within the struct name space (not in the C++ sense). You can use it and define variables or function arguments of the newly defined type by defining … Read more