In C#, the For loop is slightly faster. For loop average about 2.95 to 3.02 ms. The While loop averaged about 3.05 to 3.37 ms. As others have said, any compiler worth its salt will generate practically identical code.
Is one loop faster than the other?
In C#, the For loop is slightly faster. For loop average about 2.95 to 3.02 ms. The While loop averaged about 3.05 to 3.37 ms. Quick little console app to prove:
What is the difference between for loop and while loop?
06/05/2020 · A for loop is just syntactic sugar for a common pattern of while loop. Therefore, to answer your question, neither is faster than the other, because they're actually the same thing. They even will optimize the same loop differently depending on what comes before and after the loop.
Which loop is faster foreach or foreach in C?
When the thing inside the loop is very small (e.g. jj += ii;), such optimization makes the for loop a bit faster than the while (which typically doesn't do "unrolling"). Otherwise - no difference. update at the request of @zeroth
How fast is the while loop in PHP?
26/06/2017 · The while loop runs >3000 times faster than the for loop! I've also tried pre-generating a list for the for loop: timeit.timeit ('for i in lis: True',setup='lis = [x for x in range (10000)]', number=10000) >>> 3.638794646750142 timeit.timeit ('while i<10000: True; i+=1',setup='i=0', number=10000) >>> 0.0032454974941904524.
Is a while loop more efficient than a for loop?
As you can guess from most of these answers, the main advantage of a for loop over a while loop is readability. A for loop is a lot cleaner and a lot nicer to look at. It's also much easier to get stuck in an infinite loop with a while loop.19-Nov-2010
Are for loops faster than while loop Java?
Someone suggested to test while vs for loops, so I created some code to test whether while loops or for loops were faster; on average, over 100,000 tests, while loop was faster ~95% of the time.22-Jul-2009
Is a for loop faster than a while loop Python?
While loop cannot be iterated on Generators directly. For loop with range() uses 3 operations. range() function is implemented in C, so, its faster. On basis of disassembly, for loop is faster than while loop.11-Jul-2021
What is faster than a for loop?
Conclusions. List comprehensions are often not only more readable but also faster than using “for loops.” They can simplify your code, but if you put too much logic inside, they will instead become harder to read and understand.17-Sept-2020
Are iterators better than for loops?
Iterator and for-each loop are faster than simple for loop for collections with no random access, while in collections which allows random access there is no performance change with for-each loop/for loop/iterator.10-Mar-2021
WHY IS for loop better than while loop?
for loop: for loop provides a concise way of writing the loop structure. Unlike a while loop, a for statement consumes the initialization, condition and increment/decrement in one line thereby providing a shorter, easy to debug structure of looping.27-Jun-2019
What is faster than for loop in Python?
Array Computations are Faster than For Loops apply() in pandas. Instead, you should always prefer array computations. It only took 4.84 seconds! ... Moreover, creating a list using list(range(iterations)) is even faster than performing simple computations (6.16 seconds with for loops).
Which loop is better for or while Python?
for loops is used when you have definite itteration (the number of iterations is known). while loop is an indefinite itteration that is used when a loop repeats unkown number of times and end when some condition is met.28-May-2009
Which loop is fastest in Python?
An implied loop in map() is faster than an explicit for loop; a while loop with an explicit loop counter is even slower. Avoid calling functions written in Python in your inner loop. This includes lambdas. In-lining the inner loop can save a lot of time.
Which loop is the fastest loop?
for...of loops are hands down the fastest when it comes to small data sets, but they scale poorly for large data sets. . forEach() and for...of were close enough that neither side should hang their hat on performance alone over the other. The execution time of .01-Dec-2019
Is list comprehension always faster than for loop?
Because of differences in how Python implements for loops and list comprehension, list comprehensions are almost always faster than for loops when performing operations. Below, the same operation is performed by list comprehension and by for loop.28-Jan-2021
What is the difference between for loop and while loop?
The difference between for loop and while loop is that in for loop the number of iterations to be done is already known and is used to obtain a certain result whereas in while loop the command runs until a certain condition is reached and the statement is proved to be false.
How does a for loop start?
The For Loop Statement 1 is executed (one time) before the execution of the code block. Statement 2 defines the condition for executing the code block. Statement 3 is executed (every time) after the code block has been executed.
WHY IS FOR loop better than while?
The while loop is the more general one because its loop condition is more flexible and can be more complicated than that of a for loop. The condition of a for loop is always the same and implicit in the construction. A for loop stops if there are no more elements in the collection to treat.
Which loop is better for or while?
The for loop has overhead that the while loop does not have. You can create a for loop using a while loop construction, but you cannot in general create a while loop using a for loop construction. So in principle the while is both more efficient and more powerful than the for.
How do you speed up a Python loop?
5 tips to speed up your Python code Know the basic data structures. As already mentioned here dicts and sets use hash tables so have O (1) lookup performance. Reduce memory footprint. msg = 'line1 ' msg += 'line2 ' msg += 'line3 ' Use builtin functions and libraries. Move calculations outside the loop. Keep your code base small.
What is the difference between while loop and for loop?
In while loop if initialization is done during condition checking, then initialization is done each time the loop iterate. In 'for' loop iteration statement is written at top, hence, executes only after all statements in loop are executed. In 'while' loop, the iteration statement can be written anywhere in the loop.
Why for loop is slow in Python?
Python for loops are statically typed and interpreted. Not compiled. Java is faster because it has extra JIT acceleration features that Python does not have. In terms of doing anything in a for loop, Java cleans python's clock by being between 1 and 1000 orders of magnitude faster.
What is for loop and its syntax?
Syntax of a For Loop The initialization statement describes the starting point of the loop, where the loop variable is initialized with a starting value. The test expression is the condition until when the loop is repeated. Update statement is usually the number by which the loop variable is incremented.
What is a while loop?
The while loop tests the preconditions for the correct execution of the body. The do loop executes a body once without testing anything, and then has to deal with the aftermath, so to speak. It's more tricky to reason about.
Do while loops always execute?
A do-while and while loops are different in what functionality they provide. do-while always exectures once, while only executes if condition is true. In situations where you can use either there is no performance difference.
Preface
I've always been taught that when working in the shell, it is preferable to do while loops over for loops, and that you should not use for loops with command substitution cat 'ing a file. My understanding was that there are a number of reasons for this, including:
Test setup
I did a simple series of tests of just echoing lines of a file into /dev/null. My input is two flat files containing 100K and 1Mil IP addresses respectively. In my output below is one test, but I ran this several times with similar results each time. I was running this test on a 2013 MBA (i7, 8g Mem).
Test results
Ds-MacBook-Air:~ d$ time for i in $ (cat /tmp/ips.100k);do echo $i > /dev/null;done real 0m1.629s user 0m1.154s sys 0m0.480s Ds-MacBook-Air:~ d$ time for i in $ (cat /tmp/ips.mill);do echo $i > /dev/null;done real 0m17.567s user 0m12.414s sys 0m5.131s Ds-MacBook-Air:~ d$ time while read i;do echo $i > /dev/null;done < /tmp/ips.100k real 0m2.148s user 0m1.493s sys 0m0.655s Ds-MacBook-Air:~ d$ time while read i;do echo $i > /dev/null;done < /tmp/ips.mill real 0m21.536s user 0m14.915s sys 0m6.617s Ds-MacBook-Air:~ d$ tail -5 /tmp/ips.100k /tmp/ips.mill ==> /tmp/ips.100k <== 1.1.134.155 1.1.134.156 1.1.134.157 1.1.134.158 1.1.134.159 ==> /tmp/ips.mill <== 1.15.66.59 1.15.66.60 1.15.66.61 1.15.66.62 1.15.66.63 Ds-MacBook-Air:~ d$ wc -l /tmp/ips.100k /tmp/ips.mill 100000 /tmp/ips.100k 1000000 /tmp/ips.mill 1100000 total.
