在 C++ 中将 str[str.size()-1] 转换为整数？

Question

I have no idea how to cast str[str.size()-2] and str[str.size()-1] as integers. I need to return answers as integers.

int main()
{
    cin>>D;
    int k;
    int z;
    int*tab=new int [D];
    for (int i=0;i<D;i++)
    {
        cin>>tab[i];    
    }
    
    for (int i=0;i<D;i++)
    {
        z=silnia(tab[i]);
        string str = to_string(z);
        if (str.size()>1)
            cout<<str[str.size()-2]<<" "<<str[str.size()-1];
        else
            cout<<"0 "<<str[0];
        cout<<endl;
        suma=1;
    }    
    
    return 0;
}

Answer 1

I think you can use substr and atoi .

string std::string::substr (size_t pos = 0, size_t len = npos) const; Generate substring Returns a newly constructed string object with its value initialized to a copy of a substring of this object. The substring is the portion of the object that starts at character position pos and spans len characters (or until the end of the string, whichever comes first). http://www.cplusplus.com/reference/string/string/substr/

int atoi (const char * str); Convert string to integer Parses the C-string str interpreting its content as an integral number, which is returned as a value of type int. http://www.cplusplus.com/reference/cstdlib/atoi/

Answer 2

you can include sstream library then simply do the following:

stringstream a(str[str.size()-2]);
int x;
a >> x;

now x has the value of whatever ur string was and you can freely return x