constexpr string_view operator "" sv( const char* str, size_t len ) noexcept; constexpr u16string_view operator "" sv( const char16_t* str, size_t len ) noexcept; constexpr u32string_view operator "" ...
CSV means comma separated values. It's like a normal "txt" file with commas at regular places to separate some values. Typically the first line of CSV file is a "header", containing names of columns ...