import ctypes, msvcrt, os, win32api, ctypes.util
getMsvcrt=ctypes.cdll.msvcrt.getenv
getMsvcr_=ctypes.cdll[ctypes.util.find_msvcrt()].getenv
getMsvcrt.restype=getMsvcr_.restypy=ctypes.c_char_p

methods=['os.environ','win32','os.?etenv','msvcrt','msvcr?']
print(12*' '+''.join(['%12s'%m for m in methods]))

for m in methods:
    name,val='TEST_'+m,'foo'
    name_val='='.join([name,val])
    if   m=='os.environ': os.environ[name]=val
    elif m=='win32': win32api.SetEnvironmentVariable(name,val)
    elif m=='os.?etenv': os.putenv(name,val)
    elif m=='msvcrt': ctypes.cdll.msvcrt._putenv(name_val)
    elif m=='msvcr?': ctypes.cdll[ctypes.util.find_msvcrt()]._putenv(name_val)
    else: assert False
    res=(os.environ[name] if name in os.environ else None,win32api.GetEnvironmentVariable(name),os.getenv(name),getMsvcrt(name),getMsvcr_(name))
    res=['OK' if v==val else '--' for v in res]
    print('%12s'%m+''.join(['%12s'%r for r in res]))