View Compilation Error

0_0_18412461_31826.cpp: In function 'int main()':
0_0_18412461_31826.cpp:22:27: error: cannot pass objects of non-trivially-copyable type 'std::string {aka class std::basic_string<char>}' through '...'
             scanf("%s",str);  
                           ^
0_0_18412461_31826.cpp:42:27: error: cannot pass objects of non-trivially-copyable type 'std::string {aka class std::basic_string<char>}' through '...'
             scanf("%s",str);  
                           ^