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Passing A 2D Array to a function..

 
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Passing A 2D Array to a function..
chrisfields
post 10 Oct, 2006 - 05:32 PM
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void populateSquareMatrix(int[],int);//functionp prototype//

int SquareMatrix[ArraySize][2];//2D array//

when i try to pass the array shown above to the function populateSquareMatrix i get a syntax error:
QUOTE

>>: error C2664: 'populateSquareMatrix' : cannot convert parameter 1 from 'int [20][2]' to 'int []'

if i include a second set of [] to the prototype that causes even more errors how would i pass a 2d array to the function?

this is how i call how i call the function.

populateSquareMatrix(SquareMatrix,ArraySize);
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Amadeus
post 10 Oct, 2006 - 06:20 PM
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g++ -o drink whiskey.cpp

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http://www.cplusplus.com/doc/tutorial/arrays.html

When passing a two dimensional array to a function in that manner, C++ expects to know the number of elements in the second dimension, like so
CODE

//call the function
myArrayFunc(myarr[][10]);

There are workarounds however...you can use vectors, or even pass the array as a pointer.
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chrisfields
post 10 Oct, 2006 - 06:45 PM
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populateSquareMatrix(SquareMatrix[][2],ArraySize);

gives error:
QUOTE
'
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gregoryH
post 11 Oct, 2006 - 12:51 AM
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QUOTE(chrisfields @ 10 Oct, 2006 - 07:45 PM) *

populateSquareMatrix(SquareMatrix[][2],ArraySize);

gives>>c:\error C2059: syntax error : ']'


how did you set up the signature of the function?

the alternate is to pass as pointer to pointer ( TYPE ** variable ), but you need a little more house keeping data to go with that.
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chrisfields
post 11 Oct, 2006 - 10:38 AM
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//function definition//
void populateSquareMatrix(int array[][2],int size)
{
statements.....
}


this way worked i also had to include it in the function definition itself
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Amadeus
post 11 Oct, 2006 - 03:09 PM
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g++ -o drink whiskey.cpp

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This holds true for any function...the protottype much match the definition which must match the use.
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chrisfields
post 12 Oct, 2006 - 08:24 AM
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QUOTE(Amadeus @ 11 Oct, 2006 - 04:09 PM) *

This holds true for any function...the protottype much match the definition which must match the use.


CODE
void populateSquareMatrix(int array[ArraySize][2],int size)
{
    for(int i = 0; i < size; i++)
    {
        for(int j = 0; j < 2; j++)
        {
            printf("Row %d, Col %d: ",i,j);
            SquareMatrix[i][j]=(rand()%10);
            //SquareMatrix[][j](rand()%10);
            printf("%d,%d ",SquareMatrix[i][j]);
            printf("\n");
        }
    }



i am trying to store in 20 rows.... two numers in the 2 columns for each row
eg. row[0]=12,23
row[1]=34,56 etc etc

This post has been edited by Dark_Nexus: 31 Oct, 2006 - 10:14 PM
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amitgtbit
post 13 Oct, 2006 - 12:57 AM
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Just pass the array as function_name(arr[][],int);

and reciverd it as the pointer and than just perform the normal poniter operations as an array you will get all the answers their and if u wan a confirm than use book named pointers in C by yashwant Kanitkar.
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born2c0de
post 13 Oct, 2006 - 09:52 AM
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printf("I'm a %XR",195936478);

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QUOTE
Just pass the array as function_name(arr[][],int);


You need to specify the number of columns for the 2D Array.
Many people make this mistake.

To know why C/C++ requires us to do this, Click Here to visit my Blog for the answer.
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chrisfields
post 14 Oct, 2006 - 12:40 PM
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//function definition//
void populateSquareMatrix(int array[][2],int size)
{
    for(int row = 0; row< size; row++)
    {
        
        for(int col= 0; col< 2; col++)
        {
            SquareMatrix[row][col]=(rand()%10);
            printf("Row:%d\tCol:%d = %d ",row,col,SquareMatrix[row][col]);
            printf("\n");
        }
        
    }

}

yup it worked this way.....now here comes te hard part
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born2c0de
post 14 Oct, 2006 - 10:39 PM
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printf("I'm a %XR",195936478);

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QUOTE
//function definition//

I hope you know that // considers the entire line as a comment and cannot be closed by using // again (unlike /* ... */ )


QUOTE
now here comes te hard part

Which part are to referring to now?
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