integer extraction from string

Question

I have an input argument string const char* s I know that it starts the sequence of chars which are integers representation ,this sequence could be of any length ,

Answer 1

atoi() should work fine for this. It should stop at the first non-numeric character.

int x = atoi("23meeting")

EDIT: A comment implies that atoi() is not thread safe or is deprecated from the language. There is some discussion of the thread safety of this function here:

Why does OSX document atoi/atof as not being threadsafe?

Can someone provide a reference to atoi not being thread safe?

And as far as I can tell atoi() is in C99 which is the latest standard (7.20.1.2).