Hello All,

i don't know C.

is it possible to write a function with a function. Like

Example

test()
{
printf("Hello World");
test2()
{
printf("Welcome");
}
test2();
}

Please Explain in Detail..
Thanks in Advance...

In ISO standard C you can't use inner in functions. gcc compiler has an extension that allows that.

Is there a specific reason you are using C instead of C++?

is there a reason to do that, if you have pls share with us i am wondering about this.

regards,

It's to restrict the scope of the function, you see the idea in Java with inner classes

You can do this by placing the function in a separate source file while retaining the declaration within the function body.The linker will resolve the definition for you, something that Java won't do.
ta0kira

PS I generally prefer C over C++ whenever possible because it compiles with fewer run-time dependencies and creates linker-independent libraries.

You do not restrict the scope at all in our solution. With an example as:

there will be no symbol named test2, so you can't call it even if you declare it. (yes, you can copy the code or something else, but test2 from test, will be accesible - will have the scope just in test.

And Java does pretty much the same. (of course, you need to specify classpath, but when you compile the linker must also know all the paths to the object files).

Is there a specific reason for programming C++ instead of C?

I prefer C: no classes, no objects, no restricted access to functions, no inheritance, no interfaces and easy.

What exactly do you mean? I don't know what you're talking about, but what I'm saying is that the way I wrote it, it's perfectly legal C. Are you saying that you can't go to yet another source file and use the same function in OP's solution? That's not scope restriction, that's symbol visibility, which can't be controlled using standard C except with static and inline. If you're worried about it showing up in a library's symbol table, just use __attribute__ ((visibility("internal"))) in the function definition.
ta0kira

Sorry, mistyped. It was "your solution".

And the thing with inner functions is that there will be no symbol named as the inner function. You wouldn't be able to use test2 not even in the same file - except for the function where it is defined. The attribute thing is doing probably more or less the same thing (it is a C extension to restrict the visibility).

@neioo: you almost answered yourself. The restricted access is a big plus if the project is big and many people have to mantain it. Also, inheritance will help reuse parts of the code. I would say also that the type system is a bit better and allows you to catch more errors at compile time. Then again, you can mess up completly C++, but a bad programmer manages to do that even in C.

I thought that's what the OP wanted... An inner function for scoping purposes.

No point in using invalid C when it isn't necessary. Honestly, is it really that important to protect your own code from yourself to that level? Don't tell yourself this, but you could also just copy and paste the same embedded function into another function, so by placing it in a different file, you'd have to open that file to copy and paste it.

The only real purpose I can see for this is to protect a library, which can easily be controlled by visibility or inline.
ta0kira

I wouldn't recommend such a thing. I was just explaining why someone would want to do something like that.

I'm sorry, it was hard to me to understand the existence of the Object oriented languages. I allways though that OO programming was simply to make programmers work harder: take care about classes, its visibility, its inheritance...

Now I see that the main of object oriented languages is to make easy to maintain a huge project with a lot of functionalities and with a lot of people working on it, although it has its cost in the performance. Because in huge projects, where hundreds of people are working together, is more important and abstraction of the problem, where a lot of little changes don't not affect the whole project than the performance.

Because I work in little projects, I have never taken this point of view. But I think that a well structured program written in C can also be maintained by a lot of people, if not, how can exists Linux kernel or GNU C library (for example)?

Ok, I stop this offtopic theme

Wrong place for this discussion, but I have to disagree.
ta0kira