error: use of undeclared identifier 'localtime_s'

This error message indicates that the function "localtime_s" has not been declared, meaning that the compiler does not recognize or have access to this function. This could be due to a missing header file or library that contains the declaration for this function.

To resolve this error, you may need to include the appropriate header file or library that declares the "localtime_s" function. In C++, you can include the <ctime> header file to access time-related functions. Additionally, you may need to check that your compiler supports this function, as it may not be available on all platforms or versions of C++.