General c query

Aamir Ali

Hi,

I have to use a 2D array with diff length. one is temp1[10][33] & other is temp2[10][97] & have to pass it to same function depending upon condition.

Now when I pass array by reference in C & made a function in C, it ask for constant 2nd dimension. Like if I have to use temp1 array then in function which is to be called I have to tell that array which I am going to pass has 2nd dimension 33. Due to which I am not able to use it for temp2 array.

Any suggestion how to do it.

over 12 years ago

0 Andy Neil over 12 years ago

Guru 35565 points

From Intermediate C Programming Class Notes, Chapter 15, by Steve Summit:

Two-Dimensional (and Multidimensional) Arrays: http://www.eskimo.com/~scs/cclass/int/sx9.html

Multidimensional Arrays and Functions: http://www.eskimo.com/~scs/cclass/int/sx9a.html

0 Jens-Michael Gross over 12 years ago

Guru 227245 points

Why don't you switch the two indices? Then the second index is 10 for both.

Reason for this demand is that pointers are pointers to elements of known size (else you cannot increment the pointer). For a 2-dimensional array, you have to pass a pointer to an array. And the array needs to be of fixed size. e.g. an array of 10 INTs.
Any pointer to a single element can be runed into a pointer to an array by just adding (index*sizeof(element)) to the pointer. However, if the element size is unknown or variable, then the pointer mechanism won't work.

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General c query