Programming in C: Unit III (b): Pointers
Array of Function Pointers
with Example C Program
When an array of function pointers is made, the appropriate function is selected using an index. The code given below shows the way to define and use an array of function pointers in C.
ARRAY
OF FUNCTION POINTERS
When
an array of function pointers is made, the appropriate function is selected
using an index. The code given below shows the way to define and use an array
of function pointers in C.
Step 1:
Use typedef keyword so that 'fp' can be used as type
typedef
int (*fp) (int, int);
Step 2:
Define the array and initialize each element to NULL. This can be done in two
ways:
//
with 10 pointers to functions which return an int and take two ints
1.
fp funcArr [10] = {NULL};
2.
int (*funcArr [10]) (int, int) = {NULL};
Step 3:
Assign the function's address-'Add' and 'Subtract' funcArr1 [0] = funcArr2[1] =
Add;
funcArr [0] = &Add;
funcArr [1] = &Subtract;
Step 4:
Call the function using an index to address the function pointer
printf("%d\n",
funcArr [1] (2, 3));
//
short form
printf("%d\n",
(*funcArr [0]) (2, 3));
//
correct way
30. Write a program
to add, that uses an array of function pointers, subtract, multiply, or divide
two given numbers.
#include <stdio.h>
int sum (int a, int b);
int subtract (int a, int b);
int mul (int a, int b);
int div (int a, int b);
int (*fp [4]) (int a, int b);
int main (void)
{
int result;
int num1, num2, op;
fp [0] = sum;
fp [1] = subtract;
fp [2] = mul;
fp [3] = div;
printf("\n Enter the numbers:
");
scanf("%d %d", &num1,
&num2);
do
printf("\n 0: Add \n 1:
Subtract \n 2: Multiply \n 3: Divide \n 4. EXIT\n");
printf("\n\n Enter r the
operation: ");
scanf("%d", &op);
result (*fp [op]) (num1, num2);
printf("\n Result = %d",
result);
} while (op!=4);
return 0;
}
int sum (int a, int b)
{
return a + b;
}
int subtract (int a, int b)
{
return a - b;
}
int mul (int a, int b)
{
return a* b;
}
int div(int a, int b)
{
if (b)
return a / b;
else
return 0;
}
Output
Enter the numbers: 2 3
0: Add
1: Subtract
2: Multiply
3: Divide
4. EXIT
Enter the operation: 0
Result = 5
Enter the operation: 4
Programming in C: Unit III (b): Pointers : Tag: : with Example C Program - Array of Function Pointers
Programming in C: Unit III (b): Pointers
Under Subject
Programming in C
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