some basic question about C

what is the difference between the two:

Code:

---

int main (void)
{
return 0;
}

and

int main ()
{
return 0;
}

---

and can someone explain what does a destructive and non-destructive function mean?
thx very much

One specifies that there are no parameters, and the other specifies an unknown number of parameters.

Destructive is bad. Non-destructive is not destructive. ;)


Quzah.

I've never heard of the term but a quick search turned up this:

Failure of Implicit Conventions: Determining Function Destructiveness

" destructive functions cause some change outside of the lexical scope of their function, whereas non-destructive functions do not cause changes outside of their lexical scope."

void specifies no arguments.

Code:

---

#include<stdio.h>
#include<stdlib.h>
        static int i=1;
int main()
{
        printf("function");
        if(i++==5)
              exit(0);
        main(2);
}

---

In the above code I didn't use void in the main function.
I called the main function with the argument 2.So the message "function" will get printed for five times.

If I changed the code like the following,

Code:

---

#include<stdio.h>
#include<stdlib.h>
static int i=1;
int main(void)
{
        printf("hai");
        if(i++==5)
              exit(0);
        main(2);
}

---

I have used the void as a argument type.So main function wont accept any argument.So it will throw an error.

Just started to learn C programming. Does anyone know why I get a error with this code. The program runs fine in the console but in Xcode it gives me an error saying "Return type defaults to "int"" next to the main (int argc, const char* argv[]) { part of the code. Thank you for your help!

#include <stdio.h>

main (int argc, const char* argv[]) {

int i;

i = 20;


printf("Number %d is Peter's favorite number\n", i);


return 0;

}

You didn't specify a return type for main.


Quzah.