Rule 10.3, conversion of constant expression

[dg1980]

Actually, both operands are promoted to unsigned int, so on a 32bit processor you compare 0x000000FFh with 0xFFFFFFFFh, which is always false:

Code:

19:   switch (x)
0028140E  movzx       eax,byte ptr [_x (287138h)]  
00281415  mov         dword ptr [ebp-0C4h],eax  
0028141B  cmp         dword ptr [ebp-0C4h],0FFFFFFFFh  
00281422  je          foo+36h (281426h)  
00281424  jmp         foo+4Dh (28143Dh)

(C99 6.8.4.2 Item 5 and 6.3.8.1).