I've made a test, and I tried to pass a number to an int pointer like this:
void mega_pointer(int *********number)
{
*********number = 1337;
}
But I have a segmentation fault. I don't understand. Can somebody help me ?
EDIT : I add my main :
int main(void)
{
int ********number;
mega_pointer(&number);
printf("Result = %d\n", ********number);
return 0;
}
PS : Sorry for your eye, I will never use 9* in a real program, it's just an experiment ^^
The important question is how do you call the function; it needs a 9 indirection chain to be called successfully. See the example
#include <stdio.h>
void mega_pointer(int *********number)
{
*********number = 1337;
}
int main() {
int i = 42;
int *p1 = &i;
int **p2 = &p1;
int ***p3 = &p2;
int ****p4 = &p3;
int *****p5 = &p4;
int ******p6 = &p5;
int *******p7 = &p6;
int ********p8 = &p7;
int *********p9 = &p8;
mega_pointer(p9);
printf("%d\n", i);
}
prints 1337
Furthermore there is error in your program, as indeed your code is wrong, and you are assigning 1337 to an lvalue of type int * (in my code this would be p1 instead of i; this however goes unnoticed if warnings are not enabled. If you compile your original code with gcc -Wall, then you get warning: assignment makes pointer from integer without a cast [enabled by default].
You don't have as many * characters in front of the assignment as you do in front of the parameter. It should be:
void mega_pointer(int *********number)
{
*********number = 1337;
}
In the case that you have the right number of those in the program, it should work fine. You just have to make sure you have valid variables which you are pointing to. For example this program works:
#include <stdio.h>
void mega_pointer(int *********number)
{
printf("%d\n", *********number);
*********number = 1337;
printf("%d\n", *********number);
}
int main()
{
int blah = 1;
int *blah1 = &blah;
int **blah2 = &blah1;
int ***blah3 = &blah2;
int ****blah4 = &blah3;
int *****blah5 = &blah4;
int ******blah6 = &blah5;
int *******blah7 = &blah6;
int ********blah8 = &blah7;
int *********blah9 = &blah8;
mega_pointer(blah9);
return 0;
}
It prints:
1
1337
As expected.
Your code works, but you have to set-up the pointers correctly first:
#include <stdio.h>
static void mega_pointer(int *********number)
{
*********number = 1337;
}
int main(int argc, char **argv) {
int a = 0;
int *p1, **p2, ***p3, ****p4, *****p5, ******p6, *******p7, ********p8, *********p9;
p1 = &a;
p2 = &p1;
p3 = &p2;
p4 = &p3;
p5 = &p4;
p6 = &p5;
p7 = &p6;
p8 = &p7;
p9 = &p8;
mega_pointer(p9);
printf("a=%d\n", a);
return 0;
}
When run:
$ clang -o p ptest.c
$ ./p
a=1337
the number op "*" sign represent the number of pointing that the variable is - meaning it's a pointer to a pointer to a pointer....
you have 9 "*" in the function signature, but "only" 8 in the ********number = 1337;
if you'll do
void mega_pointer(int *********number)
{
*********number = 1337;
}
it'll work, but i would advise not to use that many pointing as it can be tricky (as you found out) and lead to truble
Segmentation fault? Segmentation fault is something happen when you try to access memory which is not associated with it, or may doesn't exist for program.
you can create this fault just by:
int *ptr = NULL;
*ptr = 1;
You are accessing a memory which is not associated to this program for now or may be in past.
numberis pointing to valid memory location. BTW, so many stars burnt my eyes.