What is ANSI encoding format? Is it a system default format? In what way does it differ from ASCII?
Just in case your PC is not a "Western" PC and you don't know which code page is used, you can have a look at this page: National Language Support (NLS) API Reference
[Microsoft removed this reference, take it form web-archive National Language Support (NLS) API Reference
Or you can query your registry:
C:\>reg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\CodePage /f ACP
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Nls\CodePage
ACP REG_SZ 1252
End of search: 1 match(es) found.
C:\>