
#include <ctype.h>
#include <stdio.h>
#include <string.h>

class String
    {
public:
    String(const char *s) { ... }
    String(const String &s) { ... }
    ~String() { delete str; }
    size_t length() { return len; }
    const char *text() { return str; }
    void cat(char c) { ... }
    char &sub(size_t i)
        {
        if (i > len)
            /* error */;
        return str[i];
        }
private:
    size_t len;
    char *str;
    };

int main()
    {
    size_t i;
    String s1("hello");
    String s2(s1);
    printf("s1 = %s\n", s1.text());
    printf("s2 = %s\n", s2.text());
    for (i = 0; i < s1.length(); ++i)
        s1.sub(i) = toupper(s1.sub(i));
    printf("s1 = %s\n", s1.text());
    printf("s2 = %s\n", s2.text());
    return 0;
    }
