How to read a private key with passphrase in C ++?

I have been occupying Openssl for a signed and verified project of private and public keys in C ++ , so far I have had no problem when signing and verifying with keys without a security phrase.

the commands I use are these:

openssl req -x509 -sha512 -nodes -days 730 -newkey rsa:2048 -keyout Privada.key -out Publica.crt 

(for keys without security phrase)

and

openssl req -x509 -sha512 -days 730 -newkey rsa:2048 -keyout PrivadaPass.key -out PublicaPass.crt

(for keys with security phrase)

How can I load the private key with phrase inside my application without generating an error?