C Programming - Functions - Discussion

How compiler knows _AX is accumulator and there is no return value to calling function. As explained above there is no need get the any value from outside functions. So it is clear for particular code and if same program will run in GCC compiler I got output 1. Please explain clearly. Thanks in advance.

How can prototype declaration of fun() done in main function ?

sir _ax variable is not declared in function how can it executes

What is the difference between return; and return 0; and also return();?

Where to use void main(), int main() and main()?

void main() is used when we dont have to return value because void is a return type and it does not return any value.

int main() is used when we want to return any value this will return integer type value by the os.

You can also use float before main() function if you do so it returns float type value.

Can a function be declared inside another function?

@Deepak.

Yes a function can be defined another function.

There should be a return type in the function and is it possible to declare a function inside the main function. As per me during compilation when function is encountered in the main then compiler will have no information of the function at that time. So it will give compile error.

Accumulator, data transfer bet memory locations are used in micro-controllers, IC chips, devices like washing machine & so many.

These instructions are namely used in hardware prog -ALP (assembly prog lang). AM I right ?

I have no idea why people call it accumulator what I think is this: There are many registers in the cpu and %EAX is just one among them which is used to place return values and store the syscall number while performing a syscall.

Look at this

int foo(){
__asm__("mov $0xff, %eax;");
}
main(){
printf("%d",foo());
}

Here I have put a inline asm instruction in it and what it does is moving the value 255 to register eax and you get 255(0xff) printed in main :).

That means EAX register is the place where the return value is stored.. instead of 'return value' they placed the value in the AX register directly(by _AX=blabla) ..nothing much.. this is what I think ..may be wrong.