How to pass 2D array matrix in a function in C

Question

I need to do this to persist operations on the matrix as well  Does that mean that it needs to be passed by reference    Will this suffice   void operate on matrix char matrix   20

User · Answer

I don t know what you mean by  data dont get lost   Here s how you pass a normal 2D array to a function   void myfunc int arr M  N        M is optional  but N is required         int main       int somearr M  N           myfunc somearr

User · Answer

2D array   int sum int array   COLS   int rows         3D array   int sum int array   B  C   int A         4D array   int sum int array   B  C  D   int A         and nD array   int sum int ar   B  C  D  E  F       N   int A

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Easiest Way in Passing A Variable-Length 2D Array Most clean technique for both C  amp  C   is  pass 2D array like a 1D array  then use as 2D inside the function   include  lt stdio h gt   void func int row  int col  int  matrix       int i  j      for i 0  i lt row  i             for j 0  j lt col  j                 printf  quot  d  quot     matrix   i col   j       or better  printf  quot  d  quot    matrix                       printf  quot  n quot             int main        int matrix 2  3       0  1  2    3  4  5         func 2  3  matrix 0         return 0     Internally  no matter how many dimensions an array has  C C   always maintains a 1D array  And so  we can pass any multi-dimensional array like this

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C does not really have multi-dimensional arrays  but there are several ways to simulate them  The way to pass such arrays to a function depends on the way used to simulate the multiple dimensions   1  Use an array of arrays  This can only be used if your array bounds are fully determined at compile time  or if your compiler supports VLA s    define ROWS 4  define COLS 5  void func int array ROWS  COLS       int i  j     for  i 0  i lt ROWS  i            for  j 0  j lt COLS  j                array i  j    i j               void func vla int rows  int cols  int array rows  cols       int i  j     for  i 0  i lt rows  i            for  j 0  j lt cols  j                array i  j    i j               int main       int x ROWS  COLS      func x     func vla ROWS  COLS  x       2  Use a  dynamically allocated  array of pointers to  dynamically allocated  arrays  This is used mostly when the array bounds are not known until runtime   void func int   array  int rows  int cols      int i  j     for  i 0  i lt rows  i            for  j 0  j lt cols  j                array i  j    i j               int main       int rows  cols  i    int   x        obtain values for rows  amp  cols          allocate the array      x   malloc rows   sizeof  x     for  i 0  i lt rows  i            x i    malloc cols   sizeof  x i              use the array      func x  rows  cols         deallocate the array      for  i 0  i lt rows  i            free x i          free x       3  Use a 1-dimensional array and fixup the indices  This can be used with both statically allocated  fixed-size  and dynamically allocated arrays   void func int  array  int rows  int cols      int i  j     for  i 0  i lt rows  i            for  j 0  j lt cols  j                array i cols j  i j               int main       int rows  cols    int  x        obtain values for rows  amp  cols          allocate the array      x   malloc rows   cols   sizeof  x         use the array      func x  rows  cols         deallocate the array      free x       4  Use a dynamically allocated VLA   One advantage of this over option 2 is that there is a single memory allocation  another is that less memory is needed because the array of pointers is not required    include  lt stdio h gt   include  lt stdlib h gt   include  lt time h gt   extern void func vla int rows  int cols  int array rows  cols    extern void get rows cols int  rows  int  cols   extern void dump array const char  tag  int rows  int cols  int array rows  cols     void func vla int rows  int cols  int array rows  cols         for  int i   0  i  lt  rows  i                  for  int j   0  j  lt  cols  j                          array i  j     i   1     j   1                      int main void        int rows  cols       get rows cols  amp rows   amp cols        int   array  cols    malloc rows   cols   sizeof array 0  0            error check omitted         func vla rows  cols  array       dump array  After initialization   rows  cols  array        free array       return 0     void dump array const char  tag  int rows  int cols  int array rows  cols         printf   s   dx d   n   tag  rows  cols       for  int i   0  i  lt  rows  i                  for  int j   0  j  lt  cols  j                printf   4d   array i  j            putchar   n             void get rows cols int  rows  int  cols        srand time 0                 Only acceptable because it is called once      rows   5   rand     10       cols   3   rand     12       See srand       why call it only once

[c] How to pass 2D array (matrix) in a function in C?

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