what is the difference between iterator and for loop?
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Difference between the two traversals In for-each loop, we can't modify collection, it will throw a ConcurrentModificationException on the other hand with iterator we can modify collection. Modifying a collection simply means removing an element or changing content of an item stored in the collection.
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Lists (like Java arrays) are zero based. Note that these operations may execute in time proportional to the index value for some implementations (the LinkedList class, for example). Thus, iterating over the elements in a list is typically preferable to indexing through it if the caller does not know the implementation.
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Each implementation of Iterator is unique to the collection it is iterating. These is not enough common code to warrant an abstract base class. ... This combination allows for complete freedom to implement the interface but allows for code reuse in the cases where implementations can use the abstract class.
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As you can see, iterators come in two varieties: std::iterator and const_iterator. The distinction is that a dereferenced iterator returns a pointer, while a const_iterator returns a const pointer. This means that the value referenced by a const_iterator may not be altered.
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While loop is executed only when given condition is true. Whereas, do-while loop is executed for first time irrespective of the condition.
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The main difference between a list and an array is the functions that you can perform to them. ... It does take an extra step to use arrays because they have to be declared while lists don't because they are part of Python's syntax, so lists are generally used more often between the two, which works fine most of the time.
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range() can actually be faster in some scenario if you iterating over the same sequence multiple times. xrange() has to reconstruct the integer object every time, but range() will have real integer objects. The results below shows that xrange is indeed faster, but not enough to sweat over.
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Difference between for loop and Enhanced for loop in Java In general, enhanced for loop is much easier to use and less error-prone than for loop, where you need to manage the steps manually. At the same time, for loop is much more powerful because you get the opportunity to control over looping process.
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An if statement causes the code inside the if block to execute one time IF the condition is true. A while loop causes the code inside the while block to execute over and over and over UNTIL the condition is NOT true. A for loop is actually a while loop with a special (shortcut) syntax.
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The main difference between Iterator and Enumeration is removal of the element while traversing the collection. Iterator can remove the element during traversal of collection as it has remove() method. Enumeration does not have remove() method. ... Iterator is the interface and found in the java.
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In the example of the micro-benchmark given, the reason the Enumeration is faster than Iterator is because it is tested first. ;) The longer answer is that the HotSpot compiler optimises a whole method when a loop has iterated 10,000 times.
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While loop is used in situations where we do not know how many times loop needs to be excuted beforehand. For loop is used where we already know about the number of times loop needs to be excuted. Typically for a index used in iteration.
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['On the first iteration of i=0, the inner loop executes 0 times.', 'On the first iteration of i=1, the inner loop executes 1 times.', '.', '.', 'On the first iteration of i=n-1, the inner loop executes n-1 times.']
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In Java, Iterator is an interface available in Collection framework in java. util package. It is a Java Cursor used to iterate a collection of objects. It is used to traverse a collection object elements one by one. It is available since Java 1.2 Collection Framework.
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As for infinite loops for(;;) loop is better than while(1) since while evaluates every time the condition but again it depends on the compiler.
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In Java, Iterator is an interface available in Collection framework in java. ... It is a Java Cursor used to iterate a collection of objects. It is used to traverse a collection object elements one by one. It is available since Java 1.2 Collection Framework.
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In for-each loop, we can't modify collection, it will throw a ConcurrentModificationException on the other hand with iterator we can modify collection. Modifying a collection simply means removing an element or changing content of an item stored in the collection.