Use auto to avoid redundant repetition of type names Example: ... In each case, we save writing a longish, hard-to-remember type that the compiler already knows but a programmer could get wrong. Avoid auto . for initializer lists . in cases where you know exactly which type you want . where an initializer might require conversion. https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-auto |