C Function Pointer & Struct
In C programming, a struct is a user-defined data type that is used to group variables of different types under a single name.
In C programming, a function pointer is a pointer that points to a function.
Function pointer can be used to point to a function and stored the address of a function in struct.
Function pointer is used to pass a function as an argument to another function, create callback functions, or implement a dynamic function call mechanism.
Function pointer's return type and parameter type must match the function's return type and parameter type.
Create a Simple Function Pointer in a Struct
The following example demonstrates how to create a simple function pointer in a struct and use the function pointer to call a function:
Example of function pointer in a struct
xxxxxxxxxx#include <stdio.h>// Function to add numbersint AddNumber(int x, int y) { return x + y;}// Define a structstruct Math { int (*AddNumber_ptr)(int, int); // Function pointer with the same signature as the AddNumber function};int main() { // Create an instance of the Math struct and initialize the function pointer struct Math mathObj; mathObj.AddNumber_ptr = AddNumber; // Calling the function using the function pointer and assigning the return value to result int result = mathObj.AddNumber_ptr(10, 20); printf("The sum of 10 and 20 is %d.\n", result); return 0; }Output of the above example
The sum of 10 and 20 is 30.
Explanation of code:
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int AddNumber(int x, int y) { return x + y; }: This line defines a simple function named 'AddNumber' that takes two integer parameters (int x, int y) and returns their sum as interger type. -
struct Math {.....};: This line defines a struct named 'Math'. -
int (*AddNumber_ptr)(int, int);: This line defines a function pointer variable named 'AddNumber_ptr' (an asterisk '*' is used before the variable name) and the variable is placed inside parentheses. The pointer takes two integer parameter(int, int)and returns integer type. Here 'AddNumber_ptr' pointer's return type and parameter type match with 'AddNumber' function's return type and parameter type. -
struct Math mathObj;: This creates an instance of the Math struct named 'mathObj'. -
mathObj.AddNumber_ptr = AddNumber;: This initializes the function pointer 'AddNumber_ptr' assigning the address of the 'AddNumber' function to the pointer 'AddNumber_ptr' of the Math struct. -
int result = mathObj.AddNumber_ptr(10, 20);This line calls the function 'AddNumber' using the function pointer 'AddNumber_ptr' and passing 10 and 20 as arguments and assigns the result of the function to the variable 'result'. -
printf("The sum of 10 and 20 is %d.\n", result);: This line prints the result (sum of 10 and 20) in the console.
