while loop and checking for uniqueness

[axis7818]

http://www.cplusplus.com/forum/beginner/98118/

that was an earlier post that I made, and I fixed the suggestions and my original problem, however, my program still isn't running successfully. I know the problem is in a while loop specifically this one in my GetIPs function

if(sortedWeblog.is_open())
	{
		int i = 0;
		while(std::getline(sortedWeblog, line))
		{
			IP = line.substr(0,14);
			if(IP != IPaddress[i-1])
			{
				IPaddress.push_back(IP);
			}
			i++;
		}
	}

I believe the problem has to do with the variable "i"

I have tried altering my loop countless times but I can't seem to fix it. Any help would be appreciated!

[vlad from moscow]

Try the following condition

if( i == 0 || IP != IPaddress[i-1] )

[axis7818]

I am fairly new to programming... could you explain what

if( i == o || IP != IPaddress[i-1])

would do?

also I tried changing the whole if statement to

if(sortedWeblog.is_open())
	{
		std::getline(sortedWeblog, firstline);
		std::string firstlineIP = firstline.substr(0,firstline.find(" "));
		IPaddress.push_back(firstlineIP);
		
		std::cout << IPaddress[0] << std::endl;
		system ("pause");

		for(std::size_t i = 1; i < vectorsize; i++)
		{
			std::string lineIP = IPaddress[i].substr(0, IPaddress[i].find(" "));
			if(lineIP != IPaddress[i-1])
			{
				IPaddress.push_back(lineIP);
				std::cout << IPaddress[i] << std::endl;
				system ("pause");
			}
		}	
	}

which runs through a vector i created instead of the file and its individual lines. it isn't working either.

[vlad from moscow]

I am sorry but I will not explain the code because it looks very strange that you are using standard containers and at the same time do not know elementary operators.
I think you have to read some book on C++ for beginners.

[axis7818]

It must be the way that my C++ class is being taught. I would just like to know what the "||" part of your if statement means.

[vlad from moscow]

|| is logical OR. The expression means push_back IP either when it is the first record (there is no yet any previous IP) or when the current IP is not equal to the previous IP.