{"id":25024,"date":"2020-01-30T12:15:09","date_gmt":"2020-01-30T10:15:09","guid":{"rendered":"https:\/\/www.webcodegeeks.com\/?p=25024"},"modified":"2020-06-23T14:56:20","modified_gmt":"2020-06-23T11:56:20","slug":"how-to-write-a-loop-in-python-while-and-for","status":"publish","type":"post","link":"https:\/\/www.webcodegeeks.com\/python\/how-to-write-a-loop-in-python-while-and-for\/","title":{"rendered":"How to Write a Loop in Python: While and For"},"content":{"rendered":"\n

As this series grows, I often find myself revisiting the fundamentals. For instance, today we\u2019ll be learning how to write a loop in Python. Luckily for you, there\u2019s some bonus material on recursion as well.<\/p>\n\n\n\n

In short, there are two core ways of writing a loop, while<\/code> and for<\/code>. If you\u2019re looking for a tradition loop, opt for the while<\/code> loop. Meanwhile, if you have some sequence or iterable to traverse, opt for the for<\/code> loop. If you find a scenario which gets messy with a loop (e.g. tree traversal), don\u2019t be afraid to fall back on recursion.<\/p>\n\n\n\n

Problem Description<\/h2>\n\n\n\n

When you first get into programming, you often go through a progression of different pieces of syntax. For instance, you might learn about printing and variables. Then, you might expand your knowledge into arithmetic and boolean expressions. If all goes well, you might even learn about conditionals.<\/p>\n\n\n\n

As time goes on, you might ask yourself \u201cbut, what if I want to do something repeatedly?\u201d Luckily, most imperative programming languages have a syntax for this called looping. Essentially, we repeat a task until we satisfy some condition.<\/p>\n\n\n\n

Of course, if you\u2019ve come from another programming language, you already know all about looping (or at least recursion). The trouble is getting used to the new syntax. Fortunately, we have several different solutions which we\u2019ll take a look at in the next section.<\/p>\n\n\n\n

Solutions<\/h2>\n\n\n\n

In this section, we\u2019ll take a look at three different ways to write a loop in Python. First, we\u2019ll look at recursion, a functional technique. Then, we\u2019ll dive into the two iterative techniques, while<\/code> and for<\/code>.<\/p>\n\n\n\n

Recursion<\/h3>\n\n\n\n

Before we dig into the various loop syntax in Python, I feel like it\u2019s important to mention recursion as a concept. After all, we don\u2019t actually need loops at all. We can get away from writing functions which reference themselves:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n<\/td>\n
\n
\n
def recurse():<\/code><\/div>\n
    <\/code>recurse()<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

In this example, we\u2019ve written a function called recurse()<\/code> which calls itself. If we run it, however, we\u2019ll get an error:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
01<\/div>\n
02<\/div>\n
03<\/div>\n
04<\/div>\n
05<\/div>\n
06<\/div>\n
07<\/div>\n
08<\/div>\n
09<\/div>\n
10<\/div>\n
11<\/div>\n
12<\/div>\n<\/td>\n
\n
\n
>>> recurse()<\/code><\/div>\n
Traceback (most recent call last):<\/code><\/div>\n
  <\/code>File <\/code>\"<pyshell#2>\"<\/code>, line <\/code>1<\/code>, in <module><\/code><\/div>\n
    <\/code>recurse()<\/code><\/div>\n
  <\/code>File <\/code>\"<pyshell#1>\"<\/code>, line <\/code>2<\/code>, in recurse<\/code><\/div>\n
    <\/code>recurse()<\/code><\/div>\n
  <\/code>File <\/code>\"<pyshell#1>\"<\/code>, line <\/code>2<\/code>, in recurse<\/code><\/div>\n
    <\/code>recurse()<\/code><\/div>\n
  <\/code>File <\/code>\"<pyshell#1>\"<\/code>, line <\/code>2<\/code>, in recurse<\/code><\/div>\n
    <\/code>recurse()<\/code><\/div>\n
  <\/code>[Previous line repeated <\/code>991<\/code> more times]<\/code><\/div>\n
RecursionError: maximum recursion depth exceeded<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Of course, this makes sense. After all, if a function calls itself, then it will call itself, then it will call itself, then it will call itself\u2026 alright, my head is spinning.<\/p>\n\n\n\n

Luckily, this is pretty easy to fix. We just need to add a condition which only calls the function under certain conditions (e.g. while the input is greater than zero):<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n<\/td>\n
\n
\n
def recurse(i):<\/code><\/div>\n
    <\/code>if<\/code> i > <\/code>0<\/code>:<\/code><\/div>\n
        <\/code>recurse(i - <\/code>1<\/code>)<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Now, if we can this function with some number, we won\u2019t crash:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n<\/td>\n
\n
\n
>>> recurse(<\/code>5<\/code>)<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

But, what is this actually doing? Well, let\u2019s try printing something:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n<\/td>\n
\n
\n
def recurse(i):<\/code><\/div>\n
    <\/code>print(f<\/code>'Input is {i}'<\/code>)<\/code><\/div>\n
    <\/code>if<\/code> i > <\/code>0<\/code>:<\/code><\/div>\n
        <\/code>recurse(i - <\/code>1<\/code>)<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Here, we used an f-string (learn more about those here<\/a>) to show the input every time this function is called:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n
5<\/div>\n
6<\/div>\n
7<\/div>\n<\/td>\n
\n
\n
>>> recurse(<\/code>5<\/code>)<\/code><\/div>\n
Input is <\/code>5<\/code><\/div>\n
Input is <\/code>4<\/code><\/div>\n
Input is <\/code>3<\/code><\/div>\n
Input is <\/code>2<\/code><\/div>\n
Input is <\/code>1<\/code><\/div>\n
Input is <\/code>0<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Check that out! We managed to create a function which executes 6 times when we enter a 5. As you can probably imagine, this mechanism can be used to do a lot of interesting things. If you\u2019re interested in learning more about recursion, I\u2019ve written an article all about it<\/a>.<\/p>\n\n\n\n

While Loop<\/h3>\n\n\n\n

With recursion out of the way, let\u2019s talking about loops. In Python, there are two main looping mechanisms: while<\/code> and for<\/code>. Typically, courses cover while<\/code> first because it\u2019s simpler. If you\u2019re familiar with if statements, a while<\/code> loop looks almost exactly the same:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n<\/td>\n
\n
\n
while<\/code> condition:<\/code><\/div>\n
    <\/code>do_thing()<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

If the condition is true, the loop body executes just like an if statement. However, after the body executes, the condition is rechecked. If the condition is still true, we drop back into the loop body once again.<\/p>\n\n\n\n

Naturally, we can write a loop which behaviors similarly to our recursion example. All we have to do is create a counter variable and count down on each iteration:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n<\/td>\n
\n
\n
i = <\/code>5<\/code><\/div>\n
while<\/code> i >= <\/code>0<\/code>:<\/code><\/div>\n
    <\/code>print(f<\/code>'Input is {i}'<\/code>)<\/code><\/div>\n
    <\/code>i -= <\/code>1<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

In this example, we create a variable called i<\/code> and give it a value of 5. Then, we kick off the loop by checking if i<\/code> is greater than or equal to 0. Since it is, we drop into the loop where we print \u201cInput is 5\u201d and decrement i<\/code>. Then, the process repeats. Of course, now i<\/code> is 4 instead of 5. Overall time, i<\/code> will decrement until it is -1, and the loop condition will fail.<\/p>\n\n\n\n

In Python, while<\/code> can be used to implement any indefinite loop. In other words, use a while<\/code> loop when you don\u2019t know how many iterations you\u2019ll have ahead of time. For example, while<\/code> loops are perfect for reading from files or prompting for input from a user. In the next section, we\u2019ll take a look at an example of a definite loop.<\/p>\n\n\n\n

For Loop<\/h3>\n\n\n\n

In many imperative languages like Java, C, and Python, there is more than one way to write a loop. For example, in Java, there are at least four different loop syntaxes that I\u2019m aware of (e.g. while<\/code>, for<\/code>, for each<\/code>, do while<\/code>). Since Python tries to keep things simple, the number of loop syntaxes are limited. As far as I know, there are only two: for<\/code> and while<\/code>.<\/p>\n\n\n\n

Now, for<\/code> loops in Python aren\u2019t like for<\/code> loops in other languages. Instead of providing a space to track an index, they operate more like for each<\/code> loops in other languages. In other words, we need something to iterate over like a list. Let\u2019s try recreating our while<\/code> loop from above:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n<\/td>\n
\n
\n
indices = [<\/code>5<\/code>, <\/code>4<\/code>, <\/code>3<\/code>, <\/code>2<\/code>, <\/code>1<\/code>, <\/code>0<\/code>]<\/code><\/div>\n
for<\/code> i in indices:<\/code><\/div>\n
    <\/code>print(f<\/code>'Input is {i}'<\/code>)<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

To make this loop work, we had to create a list to iterate over. Clearly, this isn\u2019t as convenient as the previous solution. Luckily, Python has a way generating these sort of iterables:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n<\/td>\n
\n
\n
for<\/code> i in range(<\/code>5<\/code>, -<\/code>1<\/code>, -<\/code>1<\/code>):<\/code><\/div>\n
    <\/code>print(f<\/code>'Input is {i}'<\/code>)<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Here, we\u2019ve created a loop which will count down from 5 to 0 just like all our other loops. To do that, we used the range()<\/code> function which generates a list-like structure from the inputs provided. In this case, 5 represents the inclusive starting value, the first -1 represents the exclusive ending value, and the second -1 represents the step (i.e. how many values to skip and in what direction).<\/p>\n\n\n\n

In general, for<\/code> loops are more useful for iterating over sequences like lists, strings, or generators. In other words, they don\u2019t work exactly like for<\/code> loops in other languages\u2014not without using a special function like range()<\/code>.<\/p>\n\n\n\n

Performance<\/h2>\n\n\n\n

At this point, I\u2019m not sure it makes sense to compare the performance of these three constructs, but I already wrote three solutions that do the same thing. In other words, we\u2019re just begging for a comparison. To kick things off, let\u2019s store all three of our solutions in strings:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
01<\/div>\n
02<\/div>\n
03<\/div>\n
04<\/div>\n
05<\/div>\n
06<\/div>\n
07<\/div>\n
08<\/div>\n
09<\/div>\n
10<\/div>\n
11<\/div>\n
12<\/div>\n
13<\/div>\n
14<\/div>\n
15<\/div>\n
16<\/div>\n
17<\/div>\n
18<\/div>\n
19<\/div>\n
20<\/div>\n
21<\/div>\n
22<\/div>\n<\/td>\n
\n
\n
setup = <\/code>\"\"<\/code>\"<\/code><\/div>\n
i = <\/code>5<\/code><\/div>\n
def recurse(i):<\/code><\/div>\n
    <\/code># Removed print <\/code>for<\/code> sanity<\/code><\/div>\n
    <\/code>if<\/code> i > <\/code>0<\/code>:<\/code><\/div>\n
        <\/code>recurse(i - <\/code>1<\/code>)<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n
 <\/div>\n
recursion = <\/code>\"\"<\/code>\"<\/code><\/div>\n
recurse(<\/code>5<\/code>)<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n
 <\/div>\n
while_loop = <\/code>\"\"<\/code>\"<\/code><\/div>\n
while<\/code> i >= <\/code>0<\/code>:<\/code><\/div>\n
    <\/code># Removed print <\/code>for<\/code> sanity<\/code><\/div>\n
    <\/code>i -= <\/code>1<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n
 <\/div>\n
for_loop = <\/code>\"\"<\/code>\"<\/code><\/div>\n
for<\/code> i in range(<\/code>5<\/code>, -<\/code>1<\/code>, -<\/code>1<\/code>):<\/code><\/div>\n
    <\/code>pass  # Removed print <\/code>for<\/code> sanity<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Then, we can run out test as follows:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n
5<\/div>\n
6<\/div>\n
7<\/div>\n<\/td>\n
\n
\n
>>> <\/code>import<\/code> timeit<\/code><\/div>\n
>>> min(timeit.repeat(setup=setup, stmt=recursion))<\/code><\/div>\n
0.7848201999999986<\/code><\/div>\n
>>> min(timeit.repeat(setup=setup, stmt=while_loop))<\/code><\/div>\n
0.040824499999999375<\/code><\/div>\n
>>> min(timeit.repeat(setup=setup, stmt=for_loop))<\/code><\/div>\n
0.34835850000000335<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

One thing I found really interesting was the performance of the while<\/code> loop. Then, I realized that my test was slightly inaccurate. Specifically, I had placed the i<\/code> in setup, so it became zero after the first iteration. In other words, the while<\/code> loop became a glorified if statement. When I updated my setup string, here were the results:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
01<\/div>\n
02<\/div>\n
03<\/div>\n
04<\/div>\n
05<\/div>\n
06<\/div>\n
07<\/div>\n
08<\/div>\n
09<\/div>\n
10<\/div>\n
11<\/div>\n
12<\/div>\n
13<\/div>\n
14<\/div>\n<\/td>\n
\n
\n
>>> setup = <\/code>\"\"<\/code>\"<\/code><\/div>\n
def recurse(i):<\/code><\/div>\n
    <\/code># Removed print <\/code>for<\/code> sanity<\/code><\/div>\n
    <\/code>if<\/code> i > <\/code>0<\/code>:<\/code><\/div>\n
        <\/code>recurse(i - <\/code>1<\/code>)<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n
>>> while_loop = <\/code>\"\"<\/code>\"<\/code><\/div>\n
i = <\/code>5<\/code><\/div>\n
while<\/code> i >= <\/code>0<\/code>:<\/code><\/div>\n
    <\/code># Removed print <\/code>for<\/code> sanity<\/code><\/div>\n
    <\/code>i -= <\/code>1<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n
>>> min(timeit.repeat(setup=setup, stmt=while_loop))<\/code><\/div>\n
0.3415355000000204<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Now, that\u2019s almost identical to the for<\/code> loop\u2014which makes sense to me. That said, I was reading some performance discussions on StackOverflow<\/a>, and the for<\/code> loop should be faster overall. Naturally, I had to investigate, so I updated both solutions for large numbers:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
01<\/div>\n
02<\/div>\n
03<\/div>\n
04<\/div>\n
05<\/div>\n
06<\/div>\n
07<\/div>\n
08<\/div>\n
09<\/div>\n
10<\/div>\n
11<\/div>\n
12<\/div>\n
13<\/div>\n
14<\/div>\n<\/td>\n
\n
\n
>>> for_loop = <\/code>\"\"<\/code>\"<\/code><\/div>\n
for<\/code> i in range(<\/code>100<\/code>, -<\/code>1<\/code>, -<\/code>1<\/code>):<\/code><\/div>\n
    <\/code>pass  # Removed print <\/code>for<\/code> sanity<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n
>>> min(timeit.repeat(setup=setup, stmt=for_loop))<\/code><\/div>\n
1.2956954000001133<\/code><\/div>\n
>>> while_loop = <\/code>\"\"<\/code>\"<\/code><\/div>\n
i = <\/code>100<\/code><\/div>\n
while<\/code> i >= <\/code>0<\/code>:<\/code><\/div>\n
    <\/code># Removed print <\/code>for<\/code> sanity<\/code><\/div>\n
    <\/code>i -= <\/code>1<\/code><\/div>\n
\"\"<\/code>\"<\/code><\/div>\n
>>> min(timeit.repeat(setup=setup, stmt=while_loop))<\/code><\/div>\n
4.765163399999892<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Turns out that 100 was all I was willing to wait. Otherwise, this test may have taken all day. That said, even at a number this small, there\u2019s an obvious difference in performance. Feel free to check out that discussion above for a further explanation of why.<\/p>\n\n\n\n

Challenge<\/h2>\n\n\n\n

Now that we know how to write a loop, let\u2019s try something interesting. Let\u2019s imagine we have a list of lists (aka a matrix):<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n
5<\/div>\n<\/td>\n
\n
\n
my_matrix = [<\/code><\/div>\n
    <\/code>[<\/code>3<\/code>, <\/code>5<\/code>, <\/code>2<\/code>, <\/code>4<\/code>],<\/code><\/div>\n
    <\/code>[<\/code>5<\/code>, <\/code>9<\/code>, <\/code>4<\/code>, <\/code>2<\/code>],<\/code><\/div>\n
    <\/code>[<\/code>1<\/code>, <\/code>8<\/code>, <\/code>4<\/code>, <\/code>3<\/code>]<\/code><\/div>\n
]<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

And, we want to total each row (inner list) and determine the average of all rows. Using the example above, we\u2019d get the following row totals:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n
5<\/div>\n<\/td>\n
\n
\n
my_matrix = [<\/code><\/div>\n
    <\/code>[<\/code>3<\/code>, <\/code>5<\/code>, <\/code>2<\/code>, <\/code>4<\/code>],  # <\/code>14<\/code><\/div>\n
    <\/code>[<\/code>5<\/code>, <\/code>9<\/code>, <\/code>4<\/code>, <\/code>2<\/code>],  # <\/code>20<\/code><\/div>\n
    <\/code>[<\/code>1<\/code>, <\/code>8<\/code>, <\/code>4<\/code>, <\/code>3<\/code>]   # <\/code>16<\/code><\/div>\n
]<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

Then, we\u2019d average the totals:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
1<\/div>\n<\/td>\n
\n
\n
(<\/code>14<\/code> + <\/code>20<\/code> + <\/code>16<\/code>) \/ <\/code>3<\/code>  # <\/code>16.666666666666668<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n

When we\u2019re done, we\u2019d report the result to the user.<\/p>\n\n\n\n

While this seems like a pretty straightforward task for us, how would we train the computer to do it? In other words, how would we use the various loop syntaxes to do this (hint: you\u2019ll might want to nest two loops)?<\/p>\n\n\n\n

If you come up with a solution, drop it down below in the comments. Naturally, I\u2019ll throw my own solution down there to get us started.<\/p>\n\n\n\n

A Little Recap<\/h2>\n\n\n\n

With all that out of the way, let\u2019s revisit our solutions once again:<\/p>\n\n\n\n

\n
\n\n\n\n
\n
01<\/div>\n
02<\/div>\n
03<\/div>\n
04<\/div>\n
05<\/div>\n
06<\/div>\n
07<\/div>\n
08<\/div>\n
09<\/div>\n
10<\/div>\n
11<\/div>\n
12<\/div>\n
13<\/div>\n
14<\/div>\n
15<\/div>\n
16<\/div>\n<\/td>\n
\n
\n
# Recursion<\/code><\/div>\n
def recurse(i):<\/code><\/div>\n
    <\/code>print(f<\/code>'Input is {i}'<\/code>)<\/code><\/div>\n
    <\/code>if<\/code> i > <\/code>0<\/code>:<\/code><\/div>\n
        <\/code>recurse(i - <\/code>1<\/code>)<\/code><\/div>\n
recurse(<\/code>5<\/code>)<\/code><\/div>\n
 <\/div>\n
# While loop<\/code><\/div>\n
i = <\/code>5<\/code><\/div>\n
while<\/code> i >= <\/code>0<\/code>:<\/code><\/div>\n
    <\/code>print(f<\/code>'Input is {i}'<\/code>)<\/code><\/div>\n
    <\/code>i -= <\/code>1<\/code><\/div>\n
 <\/div>\n
# For loop<\/code><\/div>\n
for<\/code> i in range(<\/code>5<\/code>, -<\/code>1<\/code>, -<\/code>1<\/code>):<\/code><\/div>\n
    <\/code>print(f<\/code>'Input is {i}'<\/code>)<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n\n\n\n
\n\n\n\n
\n

Published on Web Code Geeks with permission by Jeremy Grifski, partner at our WCG program<\/a>. See the original article here: How to Write a Loop in Python: While and For<\/a><\/p>\n

Opinions expressed by Web Code Geeks contributors are their own.<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

As this series grows, I often find myself revisiting the fundamentals. For instance, today we\u2019ll be learning how to write a loop in Python. Luckily for you, there\u2019s some bonus material on recursion as well. In short, there are two core ways of writing a loop, while and for. If you\u2019re looking for a tradition …<\/p>\n","protected":false},"author":14722,"featured_media":1651,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[53],"tags":[],"class_list":["post-25024","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-python"],"yoast_head":"\nHow to Write a Loop in Python: While and For - Web Code Geeks - 2026<\/title>\n<meta name=\"description\" content=\"As this series grows, I often find myself revisiting the fundamentals. For instance, today we\u2019ll be learning how to write a loop in Python. 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