C - Arrow Operator

Structure

• User defined data type in C/C++.
• creates a data type that can be used to group items of possibly different types into a single type.

Structure Pointer

#include<stdio.h>
 
struct Point
{
   int x, y;
};
 
int main()
{
   // A valid initialization. member x gets value 1 and y
   // gets value 2.  
   // The order of declaration is followed.
   struct Point p1 = {1, 2};
 
   // p2 is a pointer to structure p1
   struct Point *p2 = &p1;
 
   // Accessing structure members using structure pointer
   printf("%d %d", p2->x, p2->y);
   return 0;
}

// Output
// 1 2

정처기 예제

#include<stdio.h>
 
struct jsu
{
  char nae[12];
  int os, db, hab, hhab;
};
 
int main()
{
  // A valid initialization. member os gets value 95 and db
  // gets value 88.  The order of declaration is followed.
  struct jsu st[3] = {
    {"데이터1", 95, 88}, 
    {"데이터2", 84, 91}, 
    {"데이터3", 86, 75}
  };
  
  struct jsu* p;
 
  p = &st[0];

  // 구조화하면 순차적으로 자동배치 된다.
  // access field values using .
  
  printf("CHAR Access \n");
  printf("%s\n", (p) -> nae);
  printf("%s\n", (p+1) -> nae);
  printf("%s\n", (p+2) -> nae);
  
  printf("INT Access \n");
  printf("%d\n", (p) -> os);
  printf("%d\n", (p+1) -> os);
  printf("%d\n", (p+2) -> os);
  
  printf("%d\n", (p) -> db);
  printf("%d\n", (p) -> hab);
  printf("%d\n", (p) -> hhab);
  
  (p + 1)->hab = (p + 1)->os + (p + 2)->db;
  (p + 1)->hhab = (p+1)->hab + p->os + p->db;
  printf("\n");
  printf("%d\n", (p+1)->hab + (p+1)->hhab);
}

// OUTPUT
/*
CHAR Access 
데이터1
데이터2
데이터3
INT Access 
95
84
86
88
0
0

501
*/

Arrow operator in structure

// C program to show Arrow operator
// used in structure
 
#include <stdio.h>
#include <stdlib.h>
 
// Creating the structure
struct student {
    char name[80];
    int age;
    float percentage;
};
 
// Creating the structure object
struct student* emp = NULL;
 
// Driver code
int main()
{
    // Assigning memory to struct variable emp
    emp = (struct student*)
        malloc(sizeof(struct student));
 
    // Assigning value to age variable
    // of emp using arrow operator
    emp->age = 18;
 
    // Printing the assigned value to the variable
    printf("%d", emp->age);
 
    return 0;
}
// Output
// 18

Arrow operator in unions

// C program to show Arrow operator
// used in structure
 
#include <stdio.h>
#include <stdlib.h>
 
// Creating the union
union student {
    char name[80];
    int age;
    float percentage;
};
 
// Creating the union object
union student* emp = NULL;
 
// Driver code
int main()
{
    // Assigning memory to struct variable emp
    emp = (union student*)
        malloc(sizeof(union student));
 
    // Assigning value to age variable
    // of emp using arrow operator
    emp->age = 18;
 
    // DIsplaying the assigned value to the variable
    printf("%d", emp->age);
}
// Output
// 18

출처

https://www.geeksforgeeks.org/arrow-operator-in-c-c-with-examples/