std::isfinite
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header <cmath>
   | 
||
|   bool isfinite( float arg );  | 
(since C++11) | |
|   bool isfinite( double arg );  | 
(since C++11) | |
|   bool isfinite( long double arg );  | 
(since C++11) | |
Determines if the given floating point number arg has finite value i.e. it is normal, subnormal or zero, but not infinite or NAN. 
[edit] Parameters
| arg | - | floating point value | 
[edit] Return value
true value if arg has finite value, false otherwise
[edit] See also
|    (C++11)  | 
   categorizes the given floating point value   (function)  | 
|    (C++11)  | 
   checks if the given number is infinite   (function)  | 
|    (C++11)  | 
   checks if the given number is NaN  (function)  | 
|    (C++11)  | 
   checks if the given number is normal   (function)  |