Read and write to a memory location

Question

After doing lot of research in Google, I found below program

#include 

int main()
{
    int val;
    char *a = (char*) 0x1000;
          


        

Answer 1

You can't just write at any random address. You can only modify the contents of memory where your program can write.

If you need to modify contents of some variable, thats why pointers are for.

char a = 'x';
char* ptr = &a; // stored at some 0x....
*ptr = 'b'; // you just wrote at 0x....