Move the typedef struct Preprocessor Prepro; to the header the file and the definition in the c file along with the Prepro_init definition. This is will forward declare it for you with no issues. Preprocessor.h #ifndef _PREPROCESSOR_H_ #define _PREPROCESSOR_H_ #define MAX_FILES 15 typedef struct Preprocessor Prepro; void Prepro_init(Prepro* p); #endif Preprocessor.c #include “Preprocessor.h” #include <stdio.h> … Read more
Here is what Bjarne Stroustrup says about why they introduced using instead of extending typedef: The keyword using is used to get a linear notation “name followed by what it refers to.” We tried with the conventional and convoluted typedef solution, but never managed to get a complete and coherent solution until we settled on … Read more
They are the same. To quote the C++11 standard (or the draft to be specific): A typedef-name can also be introduced by an alias-declaration. The identifier following the using keyword becomes a typedef-name and the optional attribute-specifier-seq following the identifier appertains to that typedef-name. It has the same semantics as if it were introduced by … Read more
Wrap the existing namespace in a nested namespace which you then “use” in the original namespace. namespace foo { namespace bar_wrapper { enum bar { A }; } using namespace bar_wrapper; } namespace buzz { using namespace foo::bar_wrapper; }
The typedef declaration in C++ cannot be a template. However, C++11 added an alternative syntax using the using declaration to allow parametrized type aliases: template <typename T> using Bar = typename Foo<T>::Bar; Now you can use: Bar<int> x; // is a Foo<int>::Bar
Note that typedef int* intptr; const intptr x; is not the same as: const int* x; intptr is pointer to int. const intptr is constant pointer to int, not pointer to constant int. so, after a typedef pointer, i can’t make it const to the content anymore? There are some ugly ways, such as gcc’s … Read more
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
This is completely fine. The first use of struct tag like yours is a forward declaration of the struct type. Beware though that your usage of _Foo is not conforming. Identifiers with leading underscore and following capital letter are reserved. Don’t do that. Trailing underscore would be ok.
Usually you can use a cast to convert the operand to some type for which you know the right format. Your proposed solution: time_t t = time(NULL); printf(“%s”, t); clearly will not work, since time_t is a numeric type, not char*. We know, in general, that time_t is an arithmetic type. Something like this: printf(“%ld\n”, … Read more
It’s the same as typedef int foo; i.e. it defines foo to be the type int. While the grammar allows to swap typedef and int in this case, you usually would not do this because it impairs readability.