get length of `wchar_t*` in c++

Question

Please, how can I find out the length of a variable of type wchar_t* in c++?

code example below:

wchar_t* dimObjPrefix = L"retro_";

I would like to find out how many characters dimObjPrefix contains

Sorry, I should have made that clearer. I wanted the number of characters. wcslen seems to do what I want according to http://msdn.microsoft.com/en-us/library/78zh94ax(VS.71).aspx Thanks tusbar. — Jacob, May 17 '10 at 23:39
@Jacob: a `wchar_t` is not a string, and it doesn't have a length. I assume you're asking about `wchar_t*`. Those asterisks aren't just for show, you know. They can't be left out without changing the meaning of the code (and the question) — jalf, May 18 '10 at 02:29
@jalf thanks and sorry. I have edited the question to include a code sample of what I was trying to find, with asterisks included. — Jacob, May 18 '10 at 02:38
Edited question to show proper `L""` syntax for wide strings. — MSalters, May 18 '10 at 12:44
So you want the length of the block of memory that a `wchar_t*` points to. — Lightness Races in Orbit, Mar 31 '11 at 14:14
@Tomalak, no. From the question - "I would like to find out how many characters dimObjePrefix contains". Number of characters, not length of the block of memory. Plus this question has been marked as answered for almost a year. — Jacob, Mar 31 '11 at 22:32
@Jacob: You're right; I guess I was generalising. I meant to talk about a function of the length of the block of memory that the `wchar_t*` points to, with a focus on that the size of the pointer is irrelevant, and that the pointer itself contains no characters. Meanwhile, I wasn't aware that there was a time limit on contributing to SO questions; can you point me to that entry in the FAQ? — Lightness Races in Orbit, Mar 31 '11 at 23:08

score 51 · Accepted Answer · edited Apr 01 '20 at 16:09

51

If you want to know the size of a wchar_t string (wchar_t *), you want to use wcslen(3):

size_t wcslen (const wchar_t *ws);

edited Apr 01 '20 at 16:09

jameshfisher

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answered May 17 '10 at 23:21

Bertrand Marron

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Perhaps sizeof (wchar_t), or wchar_t x followed by sizeof x? – Joseph Quinsey May 17 '10 at 23:24
@Joseph, it took me a long time to realize what you meant, I edited. Thank you. Sorry for the confusion. – Bertrand Marron May 17 '10 at 23:35
Regarding sizeof(), neither K&R nor the ANSI Rationale give any reason for this idiosyncrasy about parentheses; does any SO reader happen to know? – Joseph Quinsey May 18 '10 at 02:04
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`sizeof(type)` versus `sizeof expression`. Now if `e` is an expression, then `(e)` is also an expression, so `sizeof (expression)` is implicitly also allowed. – MSalters May 18 '10 at 12:46
Is it safe to use `wcslen`? – Mayur Dec 15 '20 at 12:23

score 12 · Answer 2 · answered May 18 '10 at 13:05

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Assuming that you want to get the length of null terminated C style string, you have two options:

#include <cwchar> and use std::wcslen (dimObjPrefix);,
or #include <string> and use std::char_traits<wchar_t>::length (dimObjPrefix);.

answered May 18 '10 at 13:05

wilx

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get length of `wchar_t*` in c++

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