[Assembly] dword ptr? What does that mean?

Question

Could someone explain what this means? (Intel Syntax, x86, Windows)

and     dword ptr [ebp-4], 0

Answer 1

The "dword ptr" part is called a size directive. This page explains them, but it wasn't possible to direct-link to the correct section.

Basically, it means "the size of the target operand is 32 bits", so this will bitwise-AND the 32-bit value at the address computed by taking the contents of the ebp register and subtracting four with 0.

Answer 2

Consider the figure enclosed in this other question. ebp-4 is your first local variable and, seen as a dword pointer, it is the address of a 32 bit integer that has to be cleared. Maybe your source starts with

Object x = null;