Hello Everybody

I want to print the value of alternative element of a 2D array.
For Example-
23, 54, 76
37, 19, 28
62, 13, 19

Output should be-
23 76 19 62 19

I am trying to get this output since 5 hours. Here is my code -

``````#include <iostream.h>
#include <conio.h>
void process_Array(int Arr[][3],int x, int y);

void process_Array(int A[][3],int N, int M)
{
clrscr();
for (int R = 0; R < N; R++)
{
for (int C = 0; C < M; C=C+2)
{
cout<< A[R][C]<<" ";
}
}
cout<<endl;
cout<<endl;
for (int I = 0; I < N; I++)
{
for (int J = 0; J < M; J++)
{
cout << A[I][J]<<" ";
}
cout<<endl;
}
}
int main ()
{
int arr[3][3] ={{23, 54, 76},
{37, 19, 28},
{62, 13, 19},
};
process_Array(arr,3,3);
return 0;
}
``````

By this code I am getting this output -
23 76 37 28 62 19, actually there must be 19 which is arr[1,1].

Thank you.

You can use modular arithmetic to make a variable to take values between 0 - (n-1) when it's incremented by 2, or you can take advantage of odd-even steps of the row number, just start the col iterator(j) from 0 when the row number is even and from 1 when the row number is odd.

Using modular arithmetic as already suggested by ken, work out what expressions need to be evaluated in order to produce an output of
`arr[0][0] arr[0][2] arr[1][1] arr[2][0] arr[2][2]`

I am learning C++ I will be greatful if anyone can provide me some kind of example in codeform.
Thank you

Toggle a boolean flag, perhaps?

``````const int arr[3][3] = {
{ 23, 54, 76 },
{ 37, 19, 28 },
{ 62, 13, 19 },
} ;

bool alt = true ;
for( const auto& row : arr ) for( int i : row )
{
if(alt) std::cout << i << '\n' ;
alt = !alt ;
}
``````

maybe you can use it like this..

``````     int b[n][m];

for (i=0;i<n;i++){

if ((i%2)==0){

for (j=0;j<m;j+=2)        {

b[i][j]=2;
}

for (j=1;j<m;j+=2){
b[i][j]=4;
}
}

else if ((i%2)!=0){

for (j=1;j<m;j+=2){

b[i][j]=2;

}

for (j=0;j<m;j+=2){
b[i][j]=4;
}

}

}``````
commented: -1 for a few issues. Uncommented code. 5 years late. -3
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