What's the best way to fill multiDimensional Array

Question

I am trying to find the best way to fill 2D Array with a specific value. Is there any better way to loop the 2D Array? I tried memset doesn't work I tried std::fill but I doubt there is something wrong with my code.

void fillMultipleArray(int m, int n, int value) { int grid[m][n]; memset(grid, 0, sizeof(grid)); for (int i = 0; i < m; i++) { for (int i = 0; i < n; i++) { std::cout << grid[m][n] << std::endl; } } }

Output

-272632896 -272632896 -272632896 -272632896 -272632896 -272632896 -272632896 -272632896

Thanks in advance

@M.A haven't tested, but are you sure that doesn't just set the first one as 666 and the rest of the elements as 0? — mediocrevegetable1
– mediocrevegetable1, Commented Feb 17, 2021 at 8:44
Don't fix the code in your question, it invalidates the posted answer. — Blastfurnace
– Blastfurnace, Commented Feb 17, 2021 at 8:53

john · Accepted Answer · 2021-02-17 08:40:38Z

1

Using memset is fine, instead look carefully at your printing code, it has multiple mistakes

for (int i = 0; i< m; i++) { for (int i = 0; i< n; i++) { std::cout<< grid[m][n]<< std::endl; } }

That should be

for (int i = 0; i < m; i++) { for (int j = 0; j < n; j++) { std::cout<< grid[i][j] << std::endl; } }

It's a good lesson, when the output is wrong, it could be because your calculation is wrong, but it could just as easily be that you are printing your results wrong. Try not to make too many assumptions.

answered Feb 17, 2021 at 8:40

john

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9 Comments

ΦXocę 웃 Пepeúpa ツ Over a year ago

for (int j = 0; j < n; i++) should be j++

john Over a year ago

@ΦXocę웃Пepeúpaツ Yes I've fixed it

ymyh Over a year ago

Yea I fixed the code printing but it's still giving the same error also i tried this memset but still having the same problem memset(grid, 0, sizeof(int) mn);

ymyh Over a year ago

Yea it works if tried memset(grid, 0, sizeof(int) mn);

john Over a year ago

@youssefmyh Do you realise that int grid[m][n] ; is not legal C++? In C++ array sizes must be constants, but m and n are variables.

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