What is (void*)0?

What is (void*)0?

2) What will be the output of the program ?

 #include<stdio.h>
 int main()
 {
     char str[20] = "Hello";
     char *const p=str;
     *p='M';
     printf("%s\n", str);
     return 0;
 }

3) What will be the output of the program If the integer is 4bytes long?

 #include<stdio.h>
 int main()
 {
     int ***r, **q, *p, i=8;
     p = &i;
     q = &p;
     r = &q;
     printf("%d, %d, %d\n", *p, **q, ***r);
     return 0;
 }

4) What will be the output of the following C code?

 #include <stdio.h>
 int x = 0;
 void main()
 {
     int *const ptr = &x;
     printf("%p\n", ptr);
     ptr++;
     printf("%p\n ", ptr);
 }

5) What will be the output of the following C code?

 #include <stdio.h>
 int main()
 {
     int *ptr, a = 10;
     ptr = &a;
     *ptr += 1;
     printf("%d,%d/n", *ptr, a);
 }