Although there is a possibility to use var at a variable declaration, meaning that the variable is initialized by the first declaration automatically, you should have extreme caution using this pattern. As an example, using for instance var i = 0; initializes the variable automatically as uint8 implying that the following loop is an infinite one causing an out of gas exception in solidity.
contract TestContract {
function infiniteLoop() {
for (var i = 0; i < 1000; i++) {
...
}
}
}
