String 类

String::String() {
  data = new char[1];
  data[0] = 0;
  len = 0;
  handle = true;
}
String::String(const char *str) {
  if (str == NULL) {
    data = new char[1];
    data[0] = 0;
    len = 0;
  } else {
    len = strlen(str);
    data = new char[len + 1];
    strcpy(data, str);
  }
  handle = true;
}
String::String(const String & other) {
handle = false;
  data = other.data;
  len = other.len;
}
String::String(String & other,bool willHandle) {
if (other.handle&&willHandle){
handle =true;
other.handle=false;
  data = other.data;
  len = other.len;
}else{
    handle = true;
    len = other.len;
    data = new char[len + 1];
    strcpy(data, other.data);
}
}
String::String(int num) {
  handle = true;
  char buff[8];
  sprintf(buff, "%d", num);
  len = strlen(buff);
  data = new char[len + 1];
  strcpy(data, buff);
}
String::String(float num) {
  handle = true;
  char buff[16];
  sprintf(buff, "%f", num);
  len = strlen(buff);
  data = new char[len + 1];
  strcpy(data, buff);
}
String::~String() {
  if (data && handle) {
    delete[]data;
    data = NULL;
  }
}
String & String::operator =(const String & other) {
  this->~String();
  handle = false;
  data = other.data;
  len = other.len;
  return *this;
}
String String::operator+(const String & other) {
  char buff[len + other.len + 1];
  strcpy(buff, data);
  strcat(buff, other.data);
  return String(buff);
}
bool String::operator==(const String & other) {
  return strcmp(data, other.data) == 0;
}
char &String::operator [] (unsigned int index) {
  return *(data + index);
}
void String::operator+=(const String & other) {
if (this!=&other){
  char buff[len + 1];
  strcpy(buff, data);
    this->~String();
  handle = true;
 
  len += other.len;
  data = new char[len + 1];
  strcpy(data, buff);
  strcat(data, other.data);
}
}
void String::operator<<(String & other) {
  if (&other != this) {
    this->~String();
    handle = true;
    len = other.len;
    data = new char[len + 1];
    strcpy(data, other.data);
  }
}
char *String::operator*() {
  return data;
}
char *String::str() {
  return data;
}
inline int String::lenth() {
  return len;
}
void String::fill(char c) {
  for (int i = 0; i < len; i++) {
    *(data + i) = c;
  }
}
inline int String::print() {
  return printf(data);
}
inline int String::println() {
  return puts(data);
}