found a weird bit,
why windows return back 2 space bar when initially there is only 1 space bar from our command prompt?


let say our application name is A.EXE

result would be
D:\>A.EXE
len = 5
[65] = [A]
[46] = [.]
[69] = [E]
[88] = [X]
[69] = [E]
[0] = [ ]

now if you do A.EXE 1 2 3
D:\>A.EXE 1 2 3
len = 12
[65] = [A]
[46] = [.]
[69] = [E]
[88] = [X]
[69] = [E]
[32] = [ ]
[32] = [ ]
[49] = [1]
[32] = [ ]
[50] = [2]
[32] = [ ]
[51] = [3]
[0] = [ ]

see, windows add an extra space bar,

Why do birds sing?
Why is rain wet?

Parser of a command line must not rely on fact that every piece will be
separated by only one blank - it can be 10 blanks or 7 or whatever.
Also, blanks can be enclosed into double quotes and then they considered a part
of the command line token:

A.EXE "C:\Program Files\Microsoft" -del

cmd allows several characters other than space to terminate a program name and begin its arguments (most usefully, the slash), but the C library's rules for parsing command lines requires a space, so cmd adds one:
program/foo → CreateProcess("C:\program.exe", "program /foo", ...)
program;foo → CreateProcess("C:\program.exe", "program ;foo", ...)
program(foo → CreateProcess("C:\program.exe", "program (foo", ...)
If the character *is* a space, this means there ends up being two spaces in the command line passed to CreateProcess.

Edit: It seems this behavior changed between XP and Vista. XP's cmd removes the extra space, Vista's does not.