Linking error in passing multi-dimensional array

Question

const int v1=16;
const int v2=16;
const int u1=4;
const int u2=4;

void display(int a[u1][u2],int u1,int u2);
void calculate(int a[v1][v2],int v1,int v2,int,int,int,int);
int main()
{
    int a[16][16];
    clrscr();
    for(int i=0;i<16;i++)
    for(int j=0;j<16;j++)
    {
      cout<<"enter element at position"<<i<<j<<":";
      cin>>a[i][j];
    }
    cout<<"\n";
    calculate(a,16,16,0,3,0,3);
    calculate(a,16,16,0,3,4,7);
    calculate(a,16,16,0,3,8,11);
    calculate(a,16,16,0,3,12,15);
    calculate(a,16,16,4,7,0,3);
    calculate(a,16,16,4,7,4,7);
    calculate(a,16,16,4,7,8,11);
    calculate(a,16,16,4,7,12,15);
    calculate(a,16,16,8,11,0,3);
    calculate(a,16,16,8,11,4,7);
    calculate(a,16,16,8,11,8,11);
    calculate(a,16,16,8,11,12,15);
    calculate(a,16,16,12,15,0,3);
    calculate(a,16,16,12,15,4,7);
    calculate(a,16,16,12,15,8,11);
    calculate(a,16,16,12,15,12,15);
    getch();
    return 0;
}

void calculate(int **a,int n,int m,int il,int iu,int jl,int ju)
{
    int q[4][4],i0=0,j0=0;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            if(i>=il && i<=iu && j<=ju && j>=jl)
            {
                q[i0][j0]=a[i][j];
                if(j==ju)
                {
                    i0++;
                    j0=0;
                }
                else
                {
                    j0++;
                }
            }
        }
    }
    display(q,u1,u2);
}

The remaning of the code is given below in comments(i.e the display function) whenever I run this in turbo C++ it says

Linking error: undefined symbol display(int a[4]near*,int,int) Linking error: undefined symbol calculate(int a[16]near*,int,int,int,int,int,int)

Please help by letting me know why and what is the solution?

Two things. 1) Don't post code in the comments, it's unreadable. Instead edit your question with the new information. 2) Where exactly is `display` defined? — StoryTeller - Unslander Monica, Feb 20 '13 at 12:52
Also note that your prototype for `calculate()` does not match the implementation. (and neither does `display()`, by the looks of it) — JasonD, Feb 20 '13 at 13:00
One problem is that `int a[v1][v2]` and `int **a` are totally different types. If you compile this as C++, it sees two different `calculate` functions in your code. Please see [Passing 2D arrays](http://stackoverflow.com/questions/3911400/passing-2d-arrays?lq=1) for some options on parameter passing. — Bo Persson, Feb 20 '13 at 13:17

score 1 · Answer 1 · answered Feb 20 '13 at 13:14

This will compile.

const int v1=16;
const int v2=16;
const int u1=4;
const int u2=4;

void display(int a[u1][u2],int u1,int u2);
void calculate(int a[v1][v2],int v1,int v2,int,int,int,int);
int main()
{
    int a[16][16];
    clrscr();
    for(int i=0;i<16;i++)
    for(int j=0;j<16;j++)
    {
      cout<<"enter element at position"<<i<<j<<":";
      cin>>a[i][j];
    }
    cout<<"\n";
    calculate(a,16,16,0,3,0,3);
    calculate(a,16,16,0,3,4,7);
    calculate(a,16,16,0,3,8,11);
    calculate(a,16,16,0,3,12,15);
    calculate(a,16,16,4,7,0,3);
    calculate(a,16,16,4,7,4,7);
    calculate(a,16,16,4,7,8,11);
    calculate(a,16,16,4,7,12,15);
    calculate(a,16,16,8,11,0,3);
    calculate(a,16,16,8,11,4,7);
    calculate(a,16,16,8,11,8,11);
    calculate(a,16,16,8,11,12,15);
    calculate(a,16,16,12,15,0,3);
    calculate(a,16,16,12,15,4,7);
    calculate(a,16,16,12,15,8,11);
    calculate(a,16,16,12,15,12,15);
    getch();
    return 0;
}

void calculate(int a[v1][v2],int n,int m,int il,int iu,int jl,int ju)
{
    int q[4][4],i0=0,j0=0;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            if(i>=il && i<=iu && j<=ju && j>=jl)
            {
                q[i0][j0]=a[i][j];
                if(j==ju)
                {
                    i0++;
                    j0=0;
                }
                else
                {
                    j0++;
                }
            }
        }
    }
    display(q,u1,u2);
}

void display(int a[u1][u2],int n,int m)
{
     for(int i=0;i<n;i++)
     {
           for(int j=0;j<m;j++)
                 cout<<a[i][j]<<setw(6);
           cout<<"\n"; 
     }
}

Good Luck.

Linking error in passing multi-dimensional array

1 Answers1