# 1. 진행 ¶

• 화요일 휴강, 급히 보강
• function, 선언 후 정의
• function pointer
• void qsort(void*, size_t, size_t, int (*)(int,int));
• structure type

• 실습 : 정수 동적 배열 자료구조 int_arr을 만들자

```typedef struct
{
size_t len;
int* ptr;
} int_arr;

int_arr* init(size_t cap);

int ia_get(int_arr* ia_p, size_t idx, int val);
int ia_set(int_arr* ia_p, size_t idx);
int ia_insert(int_arr* ia_p, size_t idx, int val);
int ia_delete(int_arr* ia_p, size_t idx);
int ia_push(int_arr* ia_p, int val);
int ia_pop(int_arr* ia_p);
int ia_sort(int_arr* ia_p, int order);//ascending(if true) or desending(if false)
```

# 2. 실습 ¶

• 승진 - 작동 안되요

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

typedef struct
{
size_t len;
int* ptr;
} int_arr;

int_arr* init(size_t cap);

int ia_set(int_arr* ia_p, size_t idx, int val);
int ia_get(int_arr* ia_p, size_t idx);
int ia_insert(int_arr* ia_p, size_t idx, int val);
int ia_delete(int_arr* ia_p, size_t idx);
int ia_push(int_arr* ia_p, int val);
int ia_pop(int_arr* ia_p);
int ia_sort(int_arr* ia_p, int order);

int main(){
int_arr* arr1 = init(5);

ia_set(arr1, 2, 1);
printf("%d\n", ia_get(arr1, 2));

ia_insert(arr1, 3, 10);
ia_delete(arr1, 3);

ia_push(arr1, 5);
printf("%d\n", ia_pop(arr1));

system("pause");
return 0;
}

int_arr* init(size_t cap){
int_arr arr;
int_arr* tmp = &arr;

arr.len = cap;
arr.ptr = (int*)malloc(sizeof(int)*arr.len);
for (int i = 0; i < arr.len; i++)
arr.ptr[i] = 0;

return tmp;
}
int ia_set(int_arr* ia_p, size_t idx, int val){
ia_p->ptr[idx] = val;
return ia_p->ptr[idx];
}
int ia_get(int_arr* ia_p, size_t idx){
return ia_p->ptr[idx];
}
int ia_insert(int_arr* ia_p, size_t idx, int val){
for (int i = ia_p->len; i >= idx; i--)
ia_p->ptr[i] = ia_p->ptr[i - 1];
ia_p->ptr[idx] = val;
ia_p->len++;

return ia_p->ptr[idx];
}
int ia_delete(int_arr* ia_p, size_t idx){
int tmp = ia_p->ptr[idx - 1];

for (int i = idx - 1; i < ia_p->len - 1; i++)
ia_p->ptr[i] = ia_p->ptr[i + 1];
ia_p->len--;

return tmp;
}
int ia_push(int_arr* ia_p, int val){
ia_p->ptr[ia_p->len++] = val;

return ia_p->ptr[ia_p->len - 1];
}
int ia_pop(int_arr* ia_p){
ia_p->len--;
return ia_p->ptr[ia_p->len];
}
int ia_sort(int_arr* ia_p, int order){
int tmp;
for (int i = ia_p->len; i > 1; i--){
for (int j = 1; j < i; j++){
if (ia_p->ptr[j - 1]>ia_p->ptr[j] && order){
tmp = ia_p->ptr[j - 1];
ia_p->ptr[j - 1] = ia_p->ptr[j];
ia_p->ptr[j] = tmp;
}
}
}

return order;
}
```

# 3. 기타 / 후기 / 방명록 ¶

새싹교실/2018/C알
새싹교실/2018
• 동적할당 했으니 풀어주는 함수도 있어야 하지 않을까요? - 승진