#include <string>
#include <iostream>

int main()
{
        using namespace std;

        string str1( "abcde" );
        string str2( "fghij" );

        str1 += str2;   // connect str1 and str2
        cout << str1 << endl;

        if( str1 == "abcdefghij" )
        {
                cout << "correct" << endl;
        }
        else
        {
                cout << "uncorrect" << endl;
        }

        cout << "str1 size=" << str1.size() << endl;
        cout << "str2 size=" << str2.size() << endl;
        return 0;
}
================================
./a.exe
abcdefghij
correct
str1 size=10
str2 size=5