How to increment a pointer address and pointer's value?

Question

Let us assume,

int *p; int a = 100; p = &a; 

What will the following code actually do and how?

p++; ++p; ++*p; ++(*p); ++*(p); *p++; (*p)++; *(p)++; *++p; *(++p); 

I know, this is kind of messy in terms of coding, but I want to know what will actually happen when we code like this.

Note : Lets assume that the address of a=5120300, it is stored in pointer p whose address is 3560200. Now, what will be the value of p & a after the execution of each statement?

Answer 1

First, the ++ operator takes precedence over the * operator, and the () operators take precedence over everything else.

Second, the ++number operator is the same as the number++ operator if you're not assigning them to anything. The difference is number++ returns number and then increments number, and ++number increments first and then returns it.

Third, by increasing the value of a pointer, you're incrementing it by the sizeof its contents, that is you're incrementing it as if you were iterating in an array.

So, to sum it all up:

ptr++;    // Pointer moves to the next int position (as if it was an array) ++ptr;    // Pointer moves to the next int position (as if it was an array) ++*ptr;   // The value pointed at by ptr is incremented ++(*ptr); // The value pointed at by ptr is incremented ++*(ptr); // The value pointed at by ptr is incremented *ptr++;   // Pointer moves to the next int position (as if it was an array). But returns the old content (*ptr)++; // The value pointed at by ptr is incremented *(ptr)++; // Pointer moves to the next int position (as if it was an array). But returns the old content *++ptr;   // Pointer moves to the next int position, and then get's accessed, with your code, segfault *(++ptr); // Pointer moves to the next int position, and then get's accessed, with your code, segfault 

As there are a lot of cases in here, I might have made some mistake, please correct me if I'm wrong.

EDIT:

So I was wrong, the precedence is a little more complicated than what I wrote, view it here: http://en.cppreference.com/w/cpp/language/operator_precedence

Answer 2

checked the program and the results are as,

p++;    // use it then move to next int position ++p;    // move to next int and then use it ++*p;   // increments the value by 1 then use it  ++(*p); // increments the value by 1 then use it ++*(p); // increments the value by 1 then use it *p++;   // use the value of p then moves to next position (*p)++; // use the value of p then increment the value *(p)++; // use the value of p then moves to next position *++p;   // moves to the next int location then use that value *(++p); // moves to next location then use that value