Does a string have a limited size? assuming running on the average desktop. 

i know 
var="a"*1000000 
print var
prints 1million a's, i even try declaring the values around it
var0="a"
var1="b"
var2="c"
var1=var1*1000000
print var2 
and its a c :) but does ruby actively prevent overflow? am i thinking
about this in the wrong way?
Stephen