what does +=, -=, *= and /= stand for in Python?
what does +=, -=, *= and /= stand for in Python? and how do you use it for while loop?
loops
Accessing the index in ‘for’ loops?
Using an additional state variable, such as an index variable (which you would normally use in languages such as C or PHP), is considered non-pythonic. The better option is to use the built-in function enumerate(), available in both Python 2 and 3:
Loop through an array in JavaScript
Three main options: for (var i = 0; i < xs.length; i++) { console.log(xs[i]); } xs.forEach((x, i) => console.log(x)); for (const x of xs) { console.log(x); } Detailed examples are below. 1. Sequential for loop: Run code snippet Pros Works on every environment You can use break and continue flow control statements Cons Too verbose Imperative Easy to have off-by-one errors (sometimes also … Read more
What is the difference between range and xrange functions in Python 2.X?
In Python 2.x: range creates a list, so if you do range(1, 10000000) it creates a list in memory with 9999999 elements. xrange is a sequence object that evaluates lazily. In Python 3: range does the equivalent of Python 2’s xrange. To get the list, you have to explicitly use list(range(…)). xrange no longer exists.
Accessing the index in ‘for’ loops?
Using an additional state variable, such as an index variable (which you would normally use in languages such as C or PHP), is considered non-pythonic. The better option is to use the built-in function enumerate(), available in both Python 2 and 3:
Loop through an array in JavaScript
Yes, assuming your implementation includes the for…of feature introduced in ECMAScript 2015 (the “Harmony” release)… which is a pretty safe assumption these days. It works like this: Or better yet, since ECMAScript 2015 also provides block-scoped variables: (The variable s is different on each iteration, but can still be declared const inside the loop body as long as it isn’t modified there.) A … Read more
Python – TypeError: ‘int’ object is not iterable
Your problem is with this line: It tries to take cow[n], which returns an integer, and make it a list. This doesn’t work, as demonstrated below: Perhaps you meant to put cow[n] inside a list: See a demonstration below: Also, I wanted to address two things: Your while-statement is missing a : at the end. It is considered very dangerous to … Read more
Why there is no do while loop in python
There is no do…while loop because there is no nice way to define one that fits in the statement: indented block pattern used by every other Python compound statement. As such proposals to add such syntax have never reached agreement. Nor is there really any need to have such a construct, not when you can just do: and have the exact … Read more
Python – TypeError: ‘int’ object is not iterable
Your problem is with this line: It tries to take cow[n], which returns an integer, and make it a list. This doesn’t work, as demonstrated below: Perhaps you meant to put cow[n] inside a list: See a demonstration below: Also, I wanted to address two things: Your while-statement is missing a : at the end. It is considered very dangerous to … Read more
For-each over an array in JavaScript
TL;DR Your best bets are usually a for-of loop (ES2015+ only; spec | MDN) – simple and async-friendly forEach (ES5+ only; spec | MDN) (or its relatives some and such) – not async-friendly (but see details) a simple old-fashioned for loop – async-friendly (rarely) for-in with safeguards – async-friendly Some quick “don’t”s: Don’t use for-in … Read more