char to int in c 2b 2b

1char a = '6'; //bounded by 0 and 9
2int n1 = a - '0'; 
3int n2 = a - 48; 
4int n3 = std::stoi(&a);

1std::string s = std::to_string(number);
2char const *pchar = s.c_str();  //use char const* as target type

1int x = std::stoi("42")

1int x = character - '0'

1int x  = '9' - 48;
2// x now equals 9 as an integer

1char a = '4';
2int ia = a - '0';