Is strtok() safe to use

Question

I am reading a lot negative things about strtok(), some say it is obsolete, some say it is not thread safe, etc.

So what is the truth, can I use strtok()? and is it thread safe?

Note: I am using Visual C++.

Please refer http://stackoverflow.com/questions/4031075/strtok-function-thread-safety — Vagish, Jun 01 '15 at 09:53
Some related questions with answers are displayed to the right (look for "Related"), for example [this](http://stackoverflow.com/q/20820937/509868) — anatolyg, Jun 01 '15 at 09:55
In general you should avoid using the C standard library when writing C++ code - use proper C++ data types and idioms instead. — Paul R, Jun 01 '15 at 09:56

score 9 · Accepted Answer · answered Jun 01 '15 at 09:53

You can use it, it's a part of the standard library.

It uses internal storage that is shared across all users of the function, so no it's not thread-safe.

It also modifies the string you hand to it, which is quite scary.

I would not recommend using it, in most cases.

score 5 · Answer 2 · answered Jun 01 '15 at 09:56

strtok() is "safe" in that it is possible to use it and not have any bugs. However, if you're programming C++ rather than C, you should use C++ string facilities to mess with strings, rather than relying on the legacy C functions. Things like std::string and std::stringstream will give you far more flexibility than strtok, while making logic bugs less likely.

Rahul Tripathi · Answer 3 · 2015-06-01T10:01:47.977

As said by unwind you can use it, strtok is safe in Visual C++ but not elsewhere. One issue which is there with strtok is that static buffer is used by strtok() function while parsing, so it's not thread safe. strtok_s is an alternative for it. From here:

6.7.3.1 The strtok_s function The strtok_s function fixes two problems in the strtok function:

A new parameter, s1max, prevents strtok_s from storing outside of the string being tokenized. (The string being divided into tokens is both an input and output of the function since strtok_s stores null characters into the string.)

A new parameter, ptr, eliminates the static internal state that prevents strtok from being re-entrant (Subclause 1.1.12). (The ISO/IEC 9899 function wcstok and the ISO/IEC 9945 (POSIX) function strtok_r fix this problem identically.)

Is strtok() safe to use

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