C Function Pointer Example

function_pointer.c

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

typedef struct _user_ User;

struct _user_ {
    char *first_name;
    char *last_name;
    char *email;

    void (*setFirstName)(User *self, const char *first_name);

    void (*setLastName)(User *self, const char *last_name);

    void (*setEmail)(User *self, const char *email);

    void (*display)(User *self);
};

static void user_display(User *user) {
    printf("[*] Full Name: %s %s\n[*] Email: %s\n", user->first_name, user->last_name, user->email);
}

static void user_setFirstName(User *self, const char *first_name) {
    self->first_name = malloc((strlen(first_name) + 1) * sizeof(char));
    strcpy(self->first_name, first_name);
}

static void user_setLastName(User *self, const char *last_name) {
    self->last_name = malloc((strlen(last_name) + 1) * sizeof(char));
    strcpy(self->last_name, last_name);
}

static void user_setEmail(User *self, const char *email) {
    self->email = malloc((strlen(email) + 1) * sizeof(char));
    strcpy(self->email, email);
}

User *new_User() {
    User *user = malloc(sizeof(User));
    user->setFirstName = &user_setFirstName;
    user->setLastName = &user_setLastName;
    user->setEmail = &user_setEmail;
    user->display = &user_display;
    return user;
}

void user_destroy(User *user) {
    free(user->first_name);
    free(user->last_name);
    free(user->email);
    free(user);
}

int main() {
    User *user = new_User();
    user->setFirstName(user, "John");
    user->setLastName(user, "Smith");
    user->setEmail(user, "[email protected]");
    user->display(user);
    user_destroy(user);
    return 0;
}