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Your counter should be the position in the array and not the value of that position. Change counter < fiblist[4] to counter < 4 and change int counter = fiblist[14] to int counter = 14 to fix the problem.
This is due to the fact that C++ does not do bounds checking. Languages like Java and python have bounds checking so if you try to access an out of bounds element, they throw an error. C++ design principle was that it shouldn't be slower than the equivalent C code, and C doesn't do array bounds checking.
If we use an array index that is out of bounds, then the compiler will probably compile and even run. But, there is no guarantee to get the correct result. Result may unpredictable and it will start causing many problems that will be hard to find. Therefore, you must be careful while using array indexing.
In order to avoid the exception, first, be very careful when you iterating over the elements of an array of a list. Make sure that your code requests for valid indices. Second, consider enclosing your code inside a try-catch statement and manipulate the exception accordingly.
The only correct way is to check the index vs. the length.
An element may be assigned the value undefined. It is just silly to use it for a sentinel here. (There may be other, valid and possibly overlapping, reasons for checking for undefined, but not "for an out of bound check" -- the code in the other question will present arguably wrong results when the value of the given arg is really undefined.)
Happy coding.
You can also write:
if (index in array) {
which will return true even if array[index] is set to undefined.
Do not test for undefined. You should use the length of the array. There are cases where it simply does not work to test for undefined because undefined is a legal value for legitimate array entry. Here's a legal JS array:
var legalArray = [4, undefined, "foo"];
And you can access it like this:
var legalArray = [4, undefined, "foo"];
var result = "";
for (var i = 0; i < legalArray.length; i++) {
result += legalArray[i] + "<br>";
}
$("#result").html(result);
Generates this output:
4
undefined
foo
As seen in this jsFiddle: http://jsfiddle.net/jfriend00/J5PPe/
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