C++ MyString Class

[gflores]

I would just like someone to check this function, because I'm not sure if I did it completely right. I have a MyString class with size, capacity, and data member variables. size is like strlen. capacity is size + 1 (for the null terminator) and data is a char array.

In this code, do I need to check for null arrays? I'm not quite sure how to do this.

I'm creating a MyString instance to hold str + this->data and then I return it. I think it's a little sloppy and could maybe be implemented better. Any suggestions? Thanks!

// in testString.cpp

MyString s1;

s1 = s2 + cString; // s2 contains "hi" and cString contains "world"

// s1 should now be... "hiworld"

MyString MyString::operator + (const char* str)
{
	MyString concatStr;

	concatStr.size = this->size + strlen(str);
	concatStr.capacity = concatStr.size + 1;
	concatStr.data = new char[concatStr.capacity];

   // copies the first string
	for (int i = 0; i < this->size; i++) 
       concatStr.data[i] = this->data[i];

	// copies the second string
	for (int i = 0; i < strlen(str)+1; i++)   // plus one for the /0
        concatStr.data[i+(this->size)] = str[i];  
  
	return concatStr;	
}

[trance]

strlen is BAAAAAD! It has the potential for buffer overflows. Use strzlen.

[kjordan2001]

  trance said:

strlen is BAAAAAD! It has the potential for buffer overflows. Use strzlen.

strzlen? I've never heard of that one. I don't seem to find a manpage and a google search turns up nothing.

[gflores]

How does strlen have the potential for buffer overflow? It just returns the length of the string? Never heard of strzlen, either.

[+virtorio MVC]

  gflores said:

Never heard of strzlen, either.

Neither has the MSDN network.

[vcv]

capacity shouldnt be strlen + 1. it should be a size that is a multiple 2.

What some string libs do, is when you concatenate/modify/do any op on a string, if it needs to allocate any memory, it allocates more than it needs. that way if you add some more data that will fit within the extra room, you dont have to copy memory over and allocate new memory.

That's my only recommendation.

[trance]

  gflores said:

How does strlen have the potential for buffer overflow? It just returns the length of the string? Never heard of strzlen, either.

Sorry about that... strnlen... not strzlen. strzlen was a custom class I wrote once before strnlen.