When copying data from one array to another, the last element is copied with garbage values. How to fix it?

Question

C++ / C#

String::String() {
  m_length = 80;
  m_capacity = 160;
  m_str = new char[m_length] {};
}

void String::setStr(char* str) {
  if (m_length < strlen(str)) {
    return;
  }
  else {
    if (str != nullptr) {
      for (int i = 0; i < strlen(str); ++i) {
        m_str[i] = str[i];
      }
    }
  }
}

void String::ShrinkToFit() {
  String str;
  str.setStr(m_str);

  m_str = nullptr;
  delete[] m_str;
  
  m_str = new char[strlen(str.m_str)];
  setStr(str.m_str);
}

Answer 1

Add a line ending character (has code 0) at the end of the line. It's also better to copy using strncpy

Answer 2

Are you sure that the memory does not get corrupted in your setStr () copying only if the length of the string > length of the buffer, and you copy the entire string in its entirety, simultaneously creating memory corruption. Well, about the \0 character you have already written above. In general, there is strdup () but it is outside the standard.