functions in <locale> missing - islower() and isupper()
<p>I am trying to do a compiler using lex and yacc, but for some reason the code does not work in my VM machine in my MAC because it says that there are some functions missing from the header . Those functions are, islower() and isupper(). ECHO and yylex for some reason are also missing. I have uninstalled and installed both bison and flex for lex and yacc, but nothing fixed it.</p>

<p>The same code works fine in my VM machine in a Windows computer. So my code is not the problem. 
Here is the error<a href="https://i.stack.imgur.com/cMkcP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cMkcP.png" alt="error caused with functions missing"></a></p>