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POHow do I pass multi-dimensional arrays of unknown size into a function using pointers in c++?
 

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  1. POHow do I pass multi-dimensional arrays of unknown size into a function using pointers in c++?
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    <p>Like the question says, I am trying to pass multi-dimensional arrays into a function to print it to a file for an engineering project. The format for which the data is inputted CANNOT be changed, so please don't suggest I just input it as a different datatype.</p> <p>This particular function anticipates a two-dimensional array (although I have others with three dimensions after this one), where nothing is known about the size of the array until run-time. I know I must use pointers to point to each row of the array separately, but I have NO idea what the syntax is for passing it to the function. In the following code, the array in question is 'block'. The main function is just a little testing example I made to try to make it work:</p> <pre><code>#include&lt;fstream&gt; using namespace std; void of_write_blocks(string filename, string block_type[], int **block, int grid[][3], string grade_type[], int grade[][3], int n_blocks, int m[]) { ofstream file_out(filename.c_str(),ios::app); file_out&lt;&lt;"\nblocks\n(\n"; for(int i=0;i&lt;n_blocks;++i) { file_out&lt;&lt;" "&lt;&lt;block_type[i]&lt;&lt;" ( "; for(int j=0;j&lt;m[i];++j) file_out&lt;&lt;block[i][j]&lt;&lt;" "; file_out&lt;&lt;") ( "; file_out&lt;&lt;grid[i][0]&lt;&lt;' '&lt;&lt;grid[i][1]&lt;&lt;' '&lt;&lt;grid[i][2]&lt;&lt;" ) "; file_out&lt;&lt;grade_type[i]&lt;&lt;" ( "; file_out&lt;&lt;grade[i][0]&lt;&lt;' '&lt;&lt;grade[i][1]&lt;&lt;' '&lt;&lt;grade[i][2]&lt;&lt;" )\n"; } file_out&lt;&lt;");\n"; } //testing example: int main() { int block[6][9]; for(int i=0; i&lt;6;++i) for(int j=0; i&lt;9;++j) block[i][j] = i*j; int grid[6][3]; for(int i=0; i&lt;6;++i) for(int j=0; i&lt;3;++j) block[i][j] = i*j; int grade[6][3]; for(int i=0; i&lt;6;++i) for(int j=0; i&lt;3;++j) block[i][j] = i*j; string grade_type[6] = {"simpleGrading"}; string block_type[6] = {"hex"}; int m[6] = {8}; int n_blocks = 6; of_write_blocks("name",block_type,block,grid,grade_type,grade,n_blocks,m); } </code></pre> <p>any help is appreciated!</p>
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    1. USMike N.
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      1. POHow do I pass multi-dimensional arrays of unknown size into a function using pointers in c++?
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      1. POHow do I pass multi-dimensional arrays of unknown size into a function using pointers in c++?
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      1. POHow do I pass multi-dimensional arrays of unknown size into a function using pointers in c++?
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    1. COIn the past 25 years, I have never, not even once, had to use a multi-dimensional array. Am I missing out on something?
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      1. POHow do I pass multi-dimensional arrays of unknown size into a function using pointers in c++?
      1. USNeil Butterworth
    2. CO@Neil Butterworth try solving the maximum summ contiguous subsequence problem in three dimensions. I implemented mine in C++ with std::vectors and it required 4 dimensional arrays.
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      1. POHow do I pass multi-dimensional arrays of unknown size into a function using pointers in c++?
      1. USArlen
    3. CO@user1344784 Fair enough - sounds like the kind of problem I and my various employers have had zero interest in solving. But if I were going to solve such problems, I think I'd use a language where MDAs are first-class objects, like say FORTRAN, which would almost certainly be more performant than C++ in this problem domain.
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      1. USNeil Butterworth
 

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