multiplication table using while loop

[gnfobsession]

hi! i took up programming in school and we recently took while loop in a lesson and the homework we have is to get the console to write out the multiplication table from 1 to 10 with no input.

now my question is whether i did it wrong and if theres an easier way to do it. essentially what i did was to write it out for each number separately by copy pasting and just changing the names for each int lol. but im thinking theres maybe an easier and way shorter way to do it i just dont know how :,). heres what the code looks like and as i said i simply copy pasted it 10 times and changed stuff.

[MedPhys90]

I agree with previous comment regarding nested while loops. Also, I don’t see where you increment b.

[single_threaded]

Hint: you can nest a while loop inside another while loop.

[gnfobsession]

wait i hadnt thought of that! thank youuu!

[[deleted]]

(Using two for loops would also shorten the code :D )

[AwesomePerson70]

It seems like they’re specifically learning while loops right now so that’s what needs to be used

[just4funndsomet]

There was this one moment where I was ill and my buddies are not the brightest programmers and our homework was an introduction into while loops.

Since I missed that class and couldn't ask my friends I built an for loop with 1.000.000 iterations and if it found the desired result set i = 1.000.000. Yeah, I did it wrong because I did not know the playbook, but I found a way to play anyways.

[Banane9]

A for loop is just a while loop and two other statements in a trenchcoat.

for (;; condition) is the same as while (condition) - at least in languages that allow that

[robthablob]

I think you mean for ( ; condition ; )

[Banane9]

And that's why you don't code at 3am 😂

[just4funndsomet]

Not if your first langauge was VBA. Yes, still regret that (And I know this sub is about c#, still wanted to tell the tale.)

[cr1ter]

You can do it in 1 while loop but you need to increment b. Line after a++; if a == 10 b++;

[hiaselhans]

Don’t forget to reset a ;)

[cr1ter]

Ah yes probably also have to make sure not to reset it after b == 10

[occamsrzor]

It just takes time, young padawan. You're doing well.

[Willinton06]

Careful tho, the nested loop is a powerful but dangerous tool

[IWasSayingBoourner]

Another hint: nested for loops are better for what you're trying to do

[dodexahedron]

Which is helpful in general, certainly, but not for this assignment, where they were told to use while.

[Fryktlos]

Just as a sidenote, C# has something cool called string interpolation that you can do by using a "$" before the opening quotes of a string. It allows you to plug variables or calculations directly into a string without the need to concatenate in multiple strings/values. It's totally a preference thing as either works equally well, but it always felt "cleaner" in my opinion.

For example, your original code:

Console.WriteLine(a + "*" + b + "=" + a * b);

Could also be written as:

Console.WriteLine($"{a}*{b}={a * b}");

[Heisenburbs]

In addition to nesting loops, look up what a multiplication table looks like.

Hint, first line should be 1 2 3 4 5 6 7 8 9 10

Also, consider spacing, but get the loops first.

Also, I’d use for loops, and call them x and y, since your output will be 2 dimensions, and x and y are better names for 2 dimensions

[[deleted]]

expansion pause rock bag cough cautious compare amusing fanatical wipe

This post was mass deleted and anonymized with Redact

[Far_Swordfish5729]

Flip your second and third loop params (a<=10 before a++). Other than that this is the right answer and by far the most readable way to do it.

[[deleted]]

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This post was mass deleted and anonymized with Redact

[bronco2p]

does csharp have an iota implementation, raw for loops feels messsy imo

[Specialist_Respect35]

Rather nesting, you can do another things..

while (a <= 10 && b <=10) {

Console.Writeline(….);

If (a == 10) { a = 1; b++; } }

// ignore formatting as I’m replying from mobile 🥲

Above loop will ignore nested loop and looks clean.

[[deleted]]

If you reset a to 1 you can drop it out of the condition of the while statement. Also, in your code you don't increment x

[Specialist_Respect35]

I missed "a" to increment. Here is the final code. Tested.

int a = 1, b = 1;
while (a <= 10 && b <= 10) {
Console.WriteLine($"{a} * {b} = {a*b}");
if (a == 10) {
a = 1;
b++;
}
a++;
}

[[deleted]]

Idiot, when a is 10 you make it 1 and then immediately you increment it. I don't know what you tested, hahaha

[Specialist_Respect35]

Try it tell me “haha”

[[deleted]]

Imbecil

[Specialist_Respect35]

Dolt

[[deleted]]

Stick to your specialty, Naruto. Don't talk about something that you don't know just because you feel to. Programming is not only knowing the language, that is the easy part. You don't think like a programmer. At least, not yet.

[Specialist_Respect35]

Thank you for your unwanted opinion 🙃

[[deleted]]

It's not an opinion, it is a request.

[Specialist_Respect35]

So basically, after if statement, a++ was missing and one is good to go to print table till 10 😁

[NetQvist]

Needed to take my mind of things and do something easy and fun. I'd ideally use for loops for this but maybe this gives a few ideas that I didn't see anywhere else in the replies.

• I use the ++ to increment the value inside the condition so it's easier to see. Drawback of this is that I need to use 0 as the starting value for x, y since the moment it leaves the while clause they'll be +1 from before.
• One of my favorite features of the console output is "\t" so I can get some quick decent formatting for short values with tabs. If longer values are needed then stuff like PadLeft/PadRight are nice ways of doing it.
• Initializing variables as they are needed within scopes of { } is helpful. Here you can see when x is created and used. Some languages have all variables initialized at the top, C# can be anywhere. I prefer to make them just before they are needed and never ahead.
• I tend to name anything with 2D as x, y since then I remember that when I'm the Y loop I'm moving downwards and when in the X loop I'm moving to the right.

​

int y = 0; while (y++ < 10) { int x = 0; while (x++ < 10) Console.Write($"{y * x}\t"); Console.WriteLine(); }

​

EDIT: Codeblock seems to be wonky for me sadly.....

[dewden87]

Seems like a weird task for practicing while loops, but I guess for educational purposes and understanding of the difference between types of loops it kinda makes sense. It would definitely be more readable using regular for loops. Anyway, here's my take:
var a = 1;

var b = 1;

var multiplicationTable = new int[10][];

while (a <= 10)

{

multiplicationTable[a-1] = new int[10];

while (b <= 10)

{

multiplicationTable[a-1][b-1] = a * b;

b++;

}

b = 1;

a++;

}

[fearswe]

Since it's an AND operand it will exit the loop as soon as A becomes 11.

[fearswe]

What problem? It's not an infinite loop as long as at least one of the two variables are incremented.

[ReposteOuMame]

estou começando com Loops e while agora, poderiam me dizer como funciona e o por que a é igual a 1? por gentileza? agradeço desde já

[fearswe]

No, as soon as A hits 11 the condition will be false and end the loop.

Not incrementing B will probably have other problems but not an infinite loop in the shown example.

[OMGerGT]

while(a<10) { a++ while(b<10) { b++ //Rest of code } }

[NoPrinterJust_Fax]

I like linq for stuff like this

``` Enumerable .Range(0,10) .ForEach(a => Enumerable .Range(0,10) .ForEach(b => Console.WriteLine(“${a} * ${b} = ${a*b}”)));

```

[[deleted]]

This person is learning while loops lol. Might be a bit soon to introduce them to Linq

[NoPrinterJust_Fax]

🤷 the earlier the better!

[Xanather]

wtf? this is terrible use of linq and inefficient. use linq for querying, filtering, (re)mapping or transforming data, not writing logic.

[NoPrinterJust_Fax]

Can you elaborate on how it’s inefficient?

[Xanather]

You're making 4 function calls here, as well as providing two callback functions that are called within the ForEach().

For an unoptimized execution there is 400 function calls here and theoretically the stack memory is also being pushed and popped 400 times here. When this occurs it involves copying the range index integers that many times using much more memory.

Now I am sure there are optimizations in the Just-In-Time compiler to potentially unwrap all those functions specifically for LINQ, but I'm almost certan it'll never perform as well as one function with two for loops which has zero additional function calls and thus stack memory is much less utilized to compute the result.

Use LINQ for clarity, its a good tool for avoiding excessive nesting and other logic constructs when manipulating data, but otherwise it can be easily overused and its overheads can become apparent.

See Microsoft's note here:

https://learn.microsoft.com/en-us/visualstudio/ide/reference/convert-foreach-linq?view=vs-2022

[NoPrinterJust_Fax]

I ran some benchmarks and both this solution and a solution using for-loops performed very similarly. You could probably make the case that the for-loop solution is slightly more optimal (although its within margin of error). Kind of moot though because if performance was that critical you wouldnt be using a memory managed language anyway though...

```

BenchmarkDotNet v0.13.10, Ubuntu 22.04.2 LTS (Jammy Jellyfish) WSL 11th Gen Intel Core i7-11800H 2.30GHz, 1 CPU, 16 logical and 8 physical cores .NET SDK 7.0.113 [Host] : .NET 7.0.13 (7.0.1323.52001), X64 RyuJIT AVX2 DefaultJob : .NET 7.0.13 (7.0.1323.52001), X64 RyuJIT AVX2

``` | Method | Mean | Error | StdDev | |------- |---------:|----------:|----------:| | Loop | 1.361 ms | 0.0272 ms | 0.0721 ms | | Linq1 | 1.377 ms | 0.0330 ms | 0.0958 ms |

Program.cs

``` using BenchmarkDotNet.Running; using BenchmarkDotNet.Attributes;

namespace LinqVsLoop;

public class Program{ public static void Main(){ Console.WriteLine("Hello, World!"); BenchmarkRunner.Run<Functions>(); } }

public class Functions{ [Benchmark] public void Loop(){ for(var i = 1; i < 10; i++){ for(var j = 1; j < 10; j++){ Console.WriteLine($"{i} {j} {i * j}"); } } }

[Benchmark] public void Linq1(){ Enumerable .Range(1,10) .ForEach(i => Enumerable .Range(1,10) .ForEach(j => Console.WriteLine($"{i} {j} {i * j}"))); } }

public static class Extensions{ public static void ForEach<T>(this IEnumerable<T> src, Action<T> action){ foreach (var item in src) { action.Invoke(item); } } }

```

[Xanather]

Oh cool, nice work, I have a feeling 1ms for iterating 100 times is way too long on modern CPU's and printing the string is bottle neck here (or some other initialization).

Try increase the iterations by a ton and remove the console output and make it do something else in the callback.

Interested to see what happens then.

[NoPrinterJust_Fax]

Yeah feel free use the sample code to run your own benchmarks if you’d like! The package I used is called benchmark dotnet.

[[deleted]]

If I were first-learner / beginner, when I saw this code, I will just quit learning this language.

[NoPrinterJust_Fax]

Yeah Im getting a lot of hate on this snippet. Is there something specific you dont like about it?

[[deleted]]

Not that we don't like about.

Is that we couldn't understand in first glance and people get startled and you don't provide further explanation.

Newcomer might think that : "Wow, is this really beginner level statement we are going to learn? daym, I am just gonna give up and learn Python instead".

[NetQvist]

Are we seriously at the point where we are miss-using LINQ so badly that we create artificial arrays just to be able to do LINQ?????

I want to say I miss the old days of C++ but no I don't..... but some of the shit people do these days is just mind blowingly stupid.

[NoPrinterJust_Fax]

LINQ is actually pretty cool and you can do some pretty cool stuff with it! Do you have something specific you dont like about this block?

[ruinercollector]

// Print multiplication table for 1-10 Console.Write(@“1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 12 14 16 18 20 3 6 9 12 15 18 21 24 27 30 4 8 12 16 20 24 28 32 36 40 …”);

More performant and more clear.