Cipher help with ciphering two words

I have the following code and it does compile and cipher. However, if I put in two words (i.e. hello world), it will only cipher hello. If a user inputs two words, as "hello world", I am to omit the space and cipher everything. I thought the isalpha function would do that for me, along with the iteration loop, but it only does the one word.

#include<iostream>
#include<string>

using std::cin;
using std::cout;
using std::endl;
using std::string;

class cypher
{
public:
        char apply_cypher(char c);
        cypher(int key1, int key2);
        void encode(string answer);
private:
        int a;
        int b;
};
cypher::cypher(int key1, int key2)
{
        a = key1;
        b = key2;
}
char cypher::apply_cypher(char c)
{
        char result = ((a*c+B)/> % 26)+97;
        return result;
}
void cypher::encode(string answer)
{
        for (std::string::iterator it = answer.begin(); it != answer.end(); ++it){
                if (isalpha(*it)){
                        *it = tolower(*it);
                        *it = apply_cypher(*it);
                        *it = toupper(*it);
                        cout << *it;
                }
        }
        cout << endl;
}
int main()
{
        int a = 5, b = 8;
        string answer;
        cout << "Enter the text you want to cipher:";
        cin >> answer;
        cout << "Cypher:";
        cypher cyph(a,B)/>;
        cyph.encode(answer);
        return 0;
}
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