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carrayspointersmultidimensional-arrayfunction-pointers
Ginu Jacob
Ginu Jacob

Reputation: 1808

Array of Array of function pointers in C

Presently i am using a function pointer array. But i need to extend it as an array of array of function pointers.The pseudo code is as below:

#include<stdio.h>


int  AnalogValue1( int a)
{
    printf("\nF: AV1 %d", a);
    return 1;
}


int  AnalogValue2( int a)
{
    printf("\nF: AV2 %d", a);
    return 1;
}

int  BinaryValue1( int a)
{
    printf("\nF: BV1 %d", a);
    return 1;
}


int  BinaryValue2( int a)
{
  printf("\nF: BV2 %d", a);
  return 1;
}
int ( *Read_AV_Props[] )(int a)
=
{
 &AnalogValue1,
 &AnalogValue2,
};

int ( *Read_BV_Props[] )(int a) =
{
 &BinaryValue1,
 &BinaryValue2
};

void main()
{
    Read_AV_Props[0](55);   
    //*(Read_Ob_Props[0])(20);

}

Here need one array of array of function pointers so that it can take the address of Read_BV_Props and Read_AV_Props. And from the main code i can call that array of array of function pointers. Is this possible in C?

Upvotes: 2

Views: 448

Answers (2)

Filipe Gon&#231;alves
Filipe Gon&#231;alves

Reputation: 21223

This is the declaration you want:

int (**myArray[])(int) = {
    Read_AV_Props,
    Read_BV_Props
};

This is an array of pointers to pointers to functions receiving int and returning int. It's not a true 2D array because Read_AV_Props and Read_BV_Props decay into a pointer to their first element, i.e., a pointer to pointer to function receiving int and returning int.

You can use it like this:

int a = (**(myArray[i]+j))(1);

Or, due to array-to-pointer decayment rule (in expressions), you could also use:

int a = (*myArray[i][j])(1);

If you want a true 2D array, you must initialize it all in one place:

int (*myArray[][])(int) = {
    { &binaryValue1, &binaryValue2 },
    { ... }
};

The usage is similar.

Or you can make an array of pointers to array of pointer to function receiving int and returning int with:

int (*(*myArray[])[sizeof(Read_AV_Props)/sizeof(*Read_AV_Props)])(int) = {
    &Read_AV_Props,
    &Read_BV_Props
};

But this assumes that Read_AV_Props and Read_BV_Props have the same size.

You can use this with:

int a = (*(*myArray[i])[j])(1);

Given your question, I believe the first option is what you're looking for.

Upvotes: 1

Devolus
Devolus

Reputation: 22104

If you need a 2D array, then you can do it like this:

#include <stdio.h>
#include <stdlib.h>

int func1(int a)
{
    return a*2;
}

int func2(int a)
{
    return a*3;
}

typedef int (*FunctionPtrType)(int a);

FunctionPtrType myArray[2][2] =
{
    // func1, func2
 { func1,  func2, },
 { func2,  func1, }
};

int main()
{
    int i;
    printf("func1 = %p\n", func1);
    printf("func2 = %p\n", func2);

    for(i = 0; i < 2; i++)
    {
        printf("%p\n", myArray[0][i]);
        printf("%p\n", myArray[1][i]);
    }

    return 0;
}

Upvotes: 0

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