2d array multiplication table | Together C & C++ | Page 1

steel tinsel Oct 21, 2023, 7:18 AM

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Im having trouble on how i can code the desire output in the picture

lime joltBOT Oct 21, 2023, 7:18 AM

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steel tinsel Oct 21, 2023, 7:19 AM

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I want to know what tips i can use to do it

tough vortex Oct 21, 2023, 7:27 AM

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One tip is that you don't need a 2d array or any array for that matter.

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Just make 2 nested for-loops and print the numbers.

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Though I suppose the assignment directly asks you to do it anyway, so I guess you have to.

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2d arrays are a pain in C++. Your options are to make a 1d array with n*m dimensions and calculate the index or make a 1d array of pointers with size n and assigne each pointer a 1d array of numbers of size m. Both ways suck.

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You can make your life a little easier by using std::vector, but you're probably not allowed to.

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Sorry that none of my "tips" are very helpful.

steel tinsel Oct 21, 2023, 7:48 AM

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its ok thank you

lime joltBOT Oct 21, 2023, 7:53 AM

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@steel tinsel Has your question been resolved? If so, type !solved :)

silent wren Oct 21, 2023, 10:50 AM

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tough vortex 2d arrays are a pain in C++. Your options are to make a 1d array with `n*m` dime...

Isn't a 2d array like int arr [1][1] (a matrix)?

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If so, he can do int arr [R][C] in which R and C are the row and column indexes. It doesn't seem like he needs to automatically fill the matrix, just type each number. So he can add a user input inside 2 nested for-loops and then print the matrix once done.

tough vortex Oct 21, 2023, 10:53 AM

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The array is dynamically sized though since the dimensions are read in at runtime.

silent wren Oct 21, 2023, 10:56 AM

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Yeah, they are.. but I don't expect this exercise to be concerned with this (since it's for a beginner). Of course, if we are to be real technical here, can't argue against what you proposed.

tough vortex Oct 21, 2023, 10:57 AM

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What size do you propose then? Make it 10x10 and call it good enough?

silent wren Oct 21, 2023, 11:13 AM

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Humn, oh well, can't get simpler than that I suppose. I completely forgot that dynamic arrs are not standard, neither in C nor in C++, my bad.

modest forum Oct 21, 2023, 11:22 AM

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tough vortex What size do you propose then? Make it 10x10 and call it good enough?

our C lecturer just slapped a fat int arr[100][100] and then had us take the required dimensions from the user lol.

silent wren Oct 21, 2023, 11:24 AM

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modest forum our C lecturer just slapped a fat `int arr[100][100]` and then had us take the r...

old problems require lazy solutions /s

modest forum Oct 21, 2023, 11:28 AM

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silent wren *old problems require lazy solutions* /s

yeah that way there's no null pointers and stuff! problem solved! /s. though later he just brushed through pointers without ever teaching what malloc and free do, dangling pointers etc because not important enough for exams, just write this stuff ez marks

hollow pulsar Oct 21, 2023, 3:16 PM

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The value is always (row+1)*(col+1), so you can do this without any arrays or loops, but you should use the array anyway if this is for homework.

#2d array multiplication table