Find common prefix among two strings.

CommonPrefix.cpp

#include <iostream>
#include <cmath>
using namespace std;

template<typename T>
T getDiff(const T a, const T b) {
        if (a >= b)
                return a;
        else if (b > a)
                return b;
}

string getPrefix(const string a, const string b) {
        string prefix;
        for (int i = 0; i < getDiff(a.length(), b.length()); i++) {
                if (a[i] == b[i]) {
                        prefix += a[i];
                }
        }
        return prefix;
}

int main () {

        string one = "Test";
        string two = "Tesj";
        cout << "a: Test, b: Tesj" << endl;
        cout << "longest portion: " << getDiff(one.length(), two.length()) << endl;
        cout << "prefix: " << getPrefix(one, two) << endl;

        return 0;
}