By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. . (You will find out how that is done in the upcoming article on object-oriented programming.). Lets see: As you can see, when a for loop iterates through a dictionary, the loop variable is assigned to the dictionarys keys. The '<' and '<=' operators are exactly the same performance cost. Does it matter if "less than" or "less than or equal to" is used? Python relies on indentation (whitespace at the beginning of a line) to define scope in the code. Strictly from a logical point of view, you have to think that < count would be more efficient than <= count for the exact reason that <= will be testing for equality as well. What's the code you've tried and it's not working? In case of C++, well, why the hell are you using C-string in the first place? Then your loop finishes that iteration and increments i so that the value is now 11. If you are not processing a sequence, then you probably want a while loop instead. Using "less than" is (usually) semantically correct, you really mean count up until i is no longer less than 10, so "less than" conveys your intentions clearly. In the original example, if i were inexplicably catapulted to a value much larger than 10, the '<' comparison would catch the error right away and exit the loop, but '!=' would continue to count up until i wrapped around past 0 and back to 10. Euler: A baby on his lap, a cat on his back thats how he wrote his immortal works (origin?). Loop continues until we reach the last item in the sequence. is used to reverse the result of the conditional statement: You can have if statements inside In this example, For Loop is used to keep the odd numbers are between 1 and maximum value. For better readability you should use a constant with an Intent Revealing Name. Maybe an infinite loop would be bad back in the 70's when you were paying for CPU time. However, using a less restrictive operator is a very common defensive programming idiom. - Wedge Oct 8, 2008 at 19:19 3 Would you consider using != instead? Other programming languages often use curly-brackets for this purpose. However, if you're talking C# or Java, I really don't think one is going to be a speed boost over the other, The few nanoseconds you gain are most likely not worth any confusion you introduce. It will return a Boolean value - either True or False. It waits until you ask for them with next(). There is no prev() function. Loops and Conditionals in Python - while Loop, for Loop & if Statement When working with collections, consider std::for_each, std::transform, or std::accumulate. Just to confirm this, I did some simple benchmarking in JavaScript. This is rarely necessary, and if the list is long, it can waste time and memory. The generated sequence has a starting point, an interval, and a terminating condition. A for loop like this is the Pythonic way to process the items in an iterable. The '<' operator is a standard and easier to read in a zero-based loop. Connect and share knowledge within a single location that is structured and easy to search. for loops should be used when you need to iterate over a sequence.
