wcscpy and memcpy

[Amon Tse]

Dear All,

I am new to unicode developement in C++. Could anyone give me an idea
whether the following (1), (2) and (3) are equivalent and correct in
semantics:

wchar_t src[] = L'ABCDE';
wchar_t tgt[100];

wcscpy(tgt, src); //(1)

memcpy(tgt, src, wcslen(src)*sizeof(wchar_t)+sizeof(L'\0')); //(2)

memcpy(tgt, src, (wcslen(src)+1)*sizeof(wchar_t)); //(3)


Thanks in advance!
Amon

 

[Ron Natalie]

wchar_t src[] = L'ABCDE';

You want quotes (") here to make a string literal.

wcscpy(tgt, src); //(1)

If you're going to insist on using character pointers and arrays here
rather than being sensible and using std::wstring, this is probably the
best way.

memcpy(tgt, src, wcslen(src)*sizeof(wchar_t)+sizeof(L'\0')); //(2)

This will work, but it is:

1. Inefficient as wcscpy probably does a better job of combinging the
copying and looking for an end of string.

2. DANGEROUS if this code ever gets moved back to C. In C the sizeof
a character constant is always sizeof(int). In C++ it's the actual size
of the character.

memcpy(tgt, src, (wcslen(src)+1)*sizeof(wchar_t)); //(3)

See #1 above.