student@ubuntu:~$
c 4/5 40 XP

Pointer Arithmetic

0%

Challenge Gallery

Quick Reference

Pointer arithmetic rules:

Expression Meaning
p + n Address n elements past p
p - n Address n elements before p
p - q Number of elements between p and q
p++ Advance p to next element
*p++ Read *p, then advance p

Equivalences:

arr[i]  ==  *(arr + i)   // Always true
&arr[i] ==  arr + i       // Always true

Common Pitfalls

  • Scaling confusion – p + 1 adds sizeof(*p) bytes, not 1 byte. The compiler scales automatically.
  • Subtracting pointers to different arrays – Only valid for pointers into the same array. Otherwise: undefined behavior.
  • Off-by-one with one-past-end – You can POINT to one-past-the-end but must NOT dereference it.
  • *p++ precedence – It’s *(p++), not (*p)++. Postfix ++ binds tighter than dereference.

Unlocks

Complete this skill to see what it unlocks.