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Is it possible to achieve temeplatization in C as it is possible in C++

开发者 https://www.devze.com 2023-04-08 23:32 出处:网络
I want to write a function in C that will accept any type of data types like int, char, float, o开发者_如何学Pythonr any other data type and do some operation on them. As this is possible in C++, is i

I want to write a function in C that will accept any type of data types like int, char, float, o开发者_如何学Pythonr any other data type and do some operation on them. As this is possible in C++, is it possible in C?


It wouldn't be pretty. Take a look at this page for an example. Lots of macro usage.


About the only thing you can do in C is macros, the poor cousins of templates. For example:

#define max(a, b) ((a) < (b) ? (b) : (a))

Note that this has a huge problem... the macro arguments are evaluated more than once. For example:

max(i+=1, i);

expands to:

((i+=1) < (i) ? (i+=1) : (i));

And the result of that expression could be all kinds of interesting things on various compilers.

So, macros are really a poor substitute for templates. You can make 'functions' that are type agnostic with them. But they come with a number of hurdles and pitfalls that make them practically useless for anything really significant. They are also rather 'hairy' and make your code a lot harder to understand than templates do.

The max example I just gave may not seem that hairy (though the doubled evaluation of arguments is certainly a surprising and difficult to deal with thing), but here is an example of declaring something like a templated vector type with macros, and it is obviously hairy.


You can create and accept a union, or you can take a pointer to the data using the generic void*. C doesn't, however, support templating as in C++.


Yes, it can be achieved by using macros. See http://www.flipcode.com/archives/Faking_Templates_In_C.shtml


You can arrange a cheat using ... e.g. with varargs function


I guess it must be a void pointer

  void *p;

Just typecast and use it. what you have asked is the limitation of c thats why it is introduced in c++

After reading your comment i guess you need an argument to send the datatype of variable

 func( void *p, int ) \\ second argument must be a datatype use sizeof to find the datatype
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