c++ - What is going wrong with my multidimentional array function? -

here have problem. want manipulate following matrix

matrix = 1---------2----------3

4---------5----------6

7---------8----------9

into

7---------8----------9

4---------5----------6

1---------2----------3

#include<iostream> using namespace std;  void f(int arrayname, int size); int main() {      int x[3][3]={{1,2,3}, {4, 5,6},{7,8,9}};      f(x, 3);      system("pause");  }  void f(int arrayname, int size) {      int holder;      for(int i=0; i<size; i++){              for(int j=0; j<size; j++)              {                      holder=arrayname[i][j];                      arrayname[i][j]=arrayname[i+2][j+2];                      arrayname[i+2][j+2]=holder;              }              }        for(int k=0; k<size; k++)              for(int l=0; l<size; l++)              {                   cout<<arrayname[k][l];                     if(l=3) cout<<"\n";              }  }    errors:  e:\semester 2\cprograms\array2.cpp in function `int main()': 10 e:\semester 2\cprograms\array2.cpp invalid conversion `int (*)[3][3]' `int' 10 e:\semester 2\cprograms\array2.cpp   initializing argument 1 of `void f(int, int)'  e:\semester 2\cprograms\array2.cpp in function `void f(int, int)': 22 e:\semester 2\cprograms\array2.cpp invalid types `int[int]' array subscript (last error repeated 5 times) 

all done before us.:)

you can assignment using standard algorithm std::reverse declared in header <algorithm>

for example

#include <iostream> #include <algorithm> #include <iterator>  int main()  {     int a[3][3] =     {         { 1, 2, 3 },          { 4, 5, 6 },         { 7, 8, 9 }     };      ( const auto &row : )     {         ( int x : row ) std::cout << x << ' ';         std::cout << std::endl;     }      std::cout << std::endl;      std::reverse( std::begin( ), std::end( ) );      ( const auto &row : )     {         ( int x : row ) std::cout << x << ' ';         std::cout << std::endl;     }      return 0; } 

the program output is

1 2 3  4 5 6  7 8 9   7 8 9  4 5 6  1 2 3  

as code function declaration

void f(int arrayname, int size); 

is wrong.

the first parameter should either reference array or pointer first element.

for example

void f( int ( &arrayname )[3][3] ); 

or

void f( int ( *arrayname )[3], int size ); 

if want write function can following way

#include <iostream>  void reverse( int ( *arrayname )[3], size_t size ) {     ( size_t = 0; < size / 2; i++ )     {         ( size_t j = 0; j < 3; j++ )         {             int tmp = arrayname[i][j];             arrayname[i][j] = arrayname[size - - 1][j];             arrayname[size - - 1][j] = tmp;         }     } }  int main()  {     int a[3][3] =     {         { 1, 2, 3 },          { 4, 5, 6 },         { 7, 8, 9 }     };      ( const auto &row : )     {         ( int x : row ) std::cout << x << ' ';         std::cout << std::endl;     }      std::cout << std::endl;      ::reverse( a, 3 );      ( const auto &row : )     {         ( int x : row ) std::cout << x << ' ';         std::cout << std::endl;     }      return 0; } 

the program output same above.