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    <p>Alright, lets just start with C for now.</p> <pre><code>void readH5Data(FILE *file, int ***sample); // this is for you to implement void writeH5Data(FILE *file, int ***sample); // this is for you to implement int main(int argc, const char *argv[]) { #define width 3 #define height 3 #define depth 3 time_t t = time(NULL); int ***sample = calloc(width, sizeof(*sample)); for (int i = 0; i &lt; width; i++) { sample[i] = calloc(height, sizeof(**sample)); for (int j = 0; j &lt; height; j++) { sample[i][j] = calloc(depth, sizeof(***sample)); } } for (int i = 0; i &lt; 1000; i++) { char *filename[64]; sprintf(filename, "mill2sort-%i-extracted.h5", i); // open the file FILE *filePtr = fopen(filename, "r"); if (filePtr == NULL || ferror(filePtr)) { fprintf(stderr, "%s\n", strerror(errno)); exit(EXIT_FAILURE); } readH5Data(filePtr, sample); fclose(filePtr); } char filename[] = "mill2sort-extracted-all"; FILE *writeFile = fopen(filename, "w"); if (writeFile == NULL || ferror(writeFile)) { fprintf(stderr, "%s\n", strerror(errno)); exit(EXIT_FAILURE); } writeH5Data(writeFile, sample); fflush(writeFile); fclose(writeFile); printf("Done in %lli seconds\n", (long long int) (time(NULL) - t)); for (int i = 0; i &lt; width; i++) { for (int j = 0; j &lt; width; j++) { free(sample[i][j]); } free(sample[i]); } free(sample); } </code></pre> <p>As long as you remember that your array is 3x3x3, you should have no problems overstepping the bounds in your 'writeH5Data' method.</p>
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    1. POC/C++ for Python programmer
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    1. USRichard J. Ross III
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    1. COI would just note that Richard is calling `calloc()` three separate times: `sample` is an array of pointers (outer `calloc`), each of which points to an array of pointers (middle `calloc`), each of which points to an array of `int`s (inner `calloc`). When I first started with C I had paper everywhere where I sketched out blocks of memory to work out what pointed to what. Also, if you really need the size of an array, in most cases you'll have to keep up with it yourself when you create the array. C doesn't know where arrays "end," in general, so `sizeof()` doesn't work.
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      1. USSam Britt
    2. COThank you for the answer, I'll study it, but I was searching for a "reference", something like https://www.cfa.harvard.edu/~jbattat/computer/python/science/idl-numpy.html. Ok, not really a "table of conversion" but something like "in C/C++ is good practice to manage arrays in this way, to pass them in this way and if you need to do <something often needed> you should do this"!
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    3. COTo be clearer, I'm searching for a "numerical reference" (but not "numerical recipies"). After I have read a lot of theory, I still don't know how to start to be productive, I have no references on how to do simple, "standard", and everyday things like manipulate multidimensional arrays and pass them to functions. After so many years of C/C++ programming in the world I think there would be a "standard" shared knowledge that suggest "To do <everyday operations> you should do this" so I haven't to reinvent the wheel, arrays manipulations and so on. I am searching for something like this!:)
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