resize multiple dimensional vector array in while loop

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Hi ALL, outside a while loop, I declare a 3-D vector array

vector Psodu;
Psodu.reserve(10);

vector > > structPersonVar(2, vector >(2,Psodu));

in the while loop, i have to change the size of the array in every iteration. First, I use the following code to release the memory for(int j=0; j < 2; j++) { for(int k =0; k < 2; k++) { vector().swap(structPersonVar[j][k]); } vector >().swap(structPersonVar[j]); } vector > >().swap(structPersonVar); Then, I resize the array

structPersonVar.resize(20);
for(j=0; j < 12; j++)
{
	structPersonVar\[j\].resize(2);
	for(int k =0; k < 2; k++)
	{
		structPersonVar\[j\]\[k\].reserve(10);	
	}
}

I am not very sure whether i am correct by doing in this way,though it works fine with testing program.