Random access of vectors

[ResidentBiscuit]

Ok, so I'm trying to randomly assign names out of a vector storing these names. But, I believe my vector is larger than the number of actual elements I have because about 10% of the time I end up getting a blank string for a name. How do I deal with this?

[ne555]

Common, you should be able to do better than that. http://www.cplusplus.com/forum/articles/40071/#msg216313
If you didn't popullated the 10% of the vector with empty strings, I would say that you are accessing out of bounds.

[ResidentBiscuit]

Ah sorry I shoulda known better than that :/ I was posting from my phone. But yea, my vector is populated from a file, and I don't populate the rest. I figured if I was accessing out of bounds, I would either get a crash or it'd print garbage.

[ascii]

Can you please share the source to your program?

[ResidentBiscuit]

Yea sure thing. Heres the function

if(names.empty() != true)
	{
		srand(time(NULL));
		int i = rand() % names.size() + 1;
		name = names[i];
	}
	else
		std::cout << "Error: Name vector not populated.";

[Athar]

+1? Why +1?

[ResidentBiscuit]

I thought rand() % x Would give me numbers from 0 to x-1?

[Athar]

And rand() % (x+1) gives you numbers from 0 to x. x is out of bounds.
rand() % x + 1 gives you numbers from 1 to x. Division takes precedence over addition.

[ResidentBiscuit]

Oh wow, that fixed it. For some reason I thought size was giving me 1 less than the number I was wanting. I must confess I don't understand the usage of modulus all the time