what is the difference between Void and int?
for example:

void main()
{
blabla;
}

....
int main()
{
blabla;
}


becaus like the "hello world" program (the only one i have made this far) uses int,
but i saw a source i downladed had void...
this is so confusing )

It means the return value of the main function. When void, the compiler assumes that you don't want to return a value and so returns 0 to the shell (or whoever was the invoker of the program/function). You can read the return value from shell directly by saying 'echo $?' after the command or implicity by && and || operators.

Writing the return value is done by saying something like
'return 27;' in the end of the function.

aha, thanks
that helped me understand it a little.
guess i have to study really hard to
understand it fully

..and "int" means that the main() function returns a integer (..., -85, 0, 1, 2, ) and "void" means that main() does not return anything. You could say that the "void"-version is less complete. If you run the compiler (gcc) on it with strict syntax-checking (gcc's -Wall -pedantic options), it will output a warning about this.

Also, the "int"-version should end with:

return 0; /* or some error code: 1,2,3... */

Because main is defined to return a integer number, and without a "return <number>" it would not comply to that.

Normally a program should return such an error code to the calling program

So arguably the nicest hello world program is:
To turn on strict syntax checking to see warnings, compile with:

gcc -Wall -pedantic -ansi -o hello hello.c

void is a C datatype, commonly used for functions that could have all kinds of data for arguments.

For instance, bsearch(), qsort() are standard parts of the C library.
They require that the last argument to the library call be a function pointer. The function prototype they expect is like this:

meaning that you can pass it pointers to anything: an int, a double, a struct, etc. That is what K & R meant when creating the void datatype.

It doesn't just mean 'nothing' it really means 'anything you want'

void main() is naughty. According to ANSI, main() should return an int.

jim mcnamara,

What you say is true about void * but not for void. void * is a different type to void, one is a pointer type and the other is not a type, unless you consider 'the lack of' as a type.

Cheers.

Seg - it's still a datatype by definition.

Sure it is by definition, I was trying to highlight the point that it is not an "anything" data type as void * .

I thought it was relevent since the thread starter was querying about the type 'void'..

Cheers