Using dword variable can only store 2^31－1, the max signed integer: 2147483647, how to declare an unsigned double word to store max unsigned integer, 2^32-1, 4294967295.

Works for me.

fasm doesn't support signed/unsigned constraints for data defines so this will also provide the same result as above:

it's strange, pls see following code I used:

myint dd 4294967295
invoke sprintf,szTemp,"%d", [myint]
invoke MessageBox,HWND_DESKTOP,szTemp,"ok",MB_OK

it return "-1", and if compare with 0, it return less than 0

cmp [myint], 0

is this normal?

Tks.

Try with this: invoke sprintf,szTemp,"%u", [myint]

Take in mind that memory contents does not understand the sign concept nor the processor actually (except for floats), it thinks it is signed and unsigned at the same time and then you pick your desired interpretation based on the EFLAGS or whatever.

if using %u the return is correct, thanks.
but how to do comparison? it treat 4294967295 as -1 if compare it with other integer.

You choose signed/unsigned results by selecting the jump to use after cmp:

ja - unsigned
jg - signed

jb - unsigned
jl - signed

Thanks