Is there any naming convention for C++ which is widely used and accepted?

No.

Everyone thinks the one they use is the best. Do something that makes sense. Nobody will complain too much so long as it's sensible.

Just don't use Hungarian. I use Camel naming convention like so ,

float PlayerLife

I go for a grazing cammel
double playerLifeForce;

I choose the Hungarian grazing Homer Simpson :
bool iDuff = true;