How to use strlen

// includes and usings

int main() {

    char * cstring = new char[6];
    cstring[0] = 'H';
    cstring[1] = 'E';
    cstring[2] = 'L';
    cstring[3] = 'L';
    cstring[4] = 'O';
    cstring[5] = '!';

    // Depending on cosmic radiation, this may work every other year.
    cout << "lenght: " << strlen(cstring) << endl;

    // Add the null byte to the end:
    cstring[5] = '\0';

    // Point in case.
    cout << "lenght: " << strlen(cstring) << endl;

    // Wait until the user figures out that "enter" closes the window.
    return cin.get();
}