Hello,
i have a question about the "*" Operator.
I know that this sign has a meaning in the context of pointers. Like this:
int *number;
But now i saw something like:
void addEnd(int num)
{
struct Node *temp1, *temp2;
temp1=(struct Node *)malloc(sizeof(struct Node));
....
....
what does this mean??
(struct Node *)..
Another example:
"new=(person*)malloc(sizeof.....) whereas person is a structure.
What does it mean, if i put a * after a structure?
Thank you in advance
Regards
Last edited by HungryMan; 05-07-2011 at 02:44 AM.
It's called casting.
return value of malloc(void*) is cast to type (struct Node*).
Which is considered poor practice.
Question 7.7b
That is a typecast ... a way to make a value appear as a different type.Originally Posted by HungryMan
As Bayint explained malloc() returns a void* (pointer to nothing) which in your exmple is beaing typecast to a pointer to a Node struct (struct Node*)
Another example of typecasts are to make a char appear as an int ..
Mostly C handles this stuff internally but when you are using typedef to create your own variable types C needs a little help so you use typecasts. There should be some pretty good information on this in any c texbook or tutorial... so a little googling and reading would be a good idea.Code:int x; char y; y= 12; x = (int) y;
Bayint mean WRT to malloc, and not casting in general.
Whatever it is considered, casting malloc is also a fairly common practice since it is a major factor in getting C source files to compile alongside C++.
C programming resources:
GNU C Function and Macro Index -- glibc reference manual
The C Book -- nice online learner guide
Current ISO draft standard
CCAN -- new CPAN like open source library repository
3 (different) GNU debugger tutorials: #1 -- #2 -- #3
cpwiki -- our wiki on sourceforge
One way to look at casting is that whenever you cast something you are telling the compiler you are wiser than it in representing the data. 99% of the times, this is not true.
1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
3. Get rid of conio.h and other antiquated DOS crap headers.
4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.
The same thing it means when you put it after int. I.e. that you want some piece of memory to be treated as a pointer to certain type.
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