2017 전산학술부 C언어 스터디 강의자료

4. int a = 10, b = 20;
int *p; // p
p = &a; // p a

5. p
!
a
!
(4byte) (4byte)

6. int a = 10, b = 20;
int *p; // p
p = &a; // p a
6000 …
6004 …
6008 …
p " 6012 6020
b " 6016 20
a " 6020 10
6024 …
6028 …
6032 …
6036 …
printf("%d", p);
6020

7. 6000 …
6004 …
6008 …
p " 6012 6020
b " 6016 20
a " 6020 10
6024 …
6028 …
6032 …
6036 …
int a = 10, b = 20;
int *p; // p
p = &a; // p a
printf("%d", *p);
10

8. int a = 10, b = 20;
int *p;
p = &a;
*p += 5;
printf("%dn", a);
15

9. int *p;
p (int *)
*p int
int *p;
int* p;
p int

10. int *a, b;
a (int *)
*a int
b int
*b
int *a, *b;
a (int *)
*a int
b (int *)
*b int

11. void swap(int *v1, int *v2) {
int temp = *v1;
*v1 = *v2;
*v2 = temp;
}
int main() {
int a = 10, b = 20; int *p = &a;
swap(_____, _____);
printf("%d %dn", a, b);
return 0;
} 20 10

12. void swap(int *v1, int *v2) {
int temp = *v1;
*v1 = *v2;
*v2 = temp;
}
int main() {
int a = 10, b = 20; int *p = &a;
swap(&a, &b); // swap(p, &b);
printf("%d %dn", a, b);
return 0;
} 20 10

13. void swap(int *v1, int *v2) {
int temp = *v1;
*v1 = *v2;
*v2 = temp;
}
int main() {
int a = 10, b = 20;
int *p = &a;
swap(&a, &b);
printf("%d %dn", a, b);
return 0;
}
3538
3542
3546
temp " 3550
v2 " 3554
v1 " 3558
p " 7580
b " 7584
a " 7588

15. 3132 …
3136 …
p " 3140
i " 3144
3148 …
arr[0]" 3152
arr[1]" 3156
arr[2]" 3160
arr[3]" 3164
arr[4]" 3168
int arr[5] = {0,};
int i, *p = arr;
printf("arr: %dn", arr);
for (i = 0; i < 5; i++)
printf("arr[%d]: %dn", i, &arr[i]);

16. 3132 …
3136 …
p " 3140
i " 3144
3148 …
arr[0]" 3152
arr[1]" 3156
arr[2]" 3160
arr[3]" 3164
arr[4]" 3168
← p + 1
← p
← p + 3
← p + 2
← p + 4

17. int arr[5] = {2, 3, 5, 7, 9};
int i;
for (i = 0; i < 5; i++)
printf("%d %dn", arr[i], *(arr + i));
*(arr + i) arr[i]

18. int strlen(char *s) {
int n;
for (n = 0; *s != '0'; s++)
n++;
return n;
}
int main() {
char str[128]; int res;
scanf("%s", str);
res = strlen(str);
printf("length: %dn", res);
return 0;
}

19. int arr[5][5];
int i, j;
for (i = 0; i < 5; i++)
for (j = 0; j < 5; j++)
arr[i][j] = i * 5 + j;
arr[0] 0 1 2 3 4
arr[1] 5 6 7 8 9
arr[2] 10 11 12 13 14
arr[3] 15 16 17 18 19
arr[4] 20 21 22 23 24

20. for (i = 0; i < 5; i++) {
for (j = 0; j < 5; j++)
printf("%2d ", *(*(arr + i) + j));
printf("n");
}
(int *)
int *pi
+1 sizeof(int)
arr[0] 0 1 2 3 4
arr[1] 5 6 7 8 9
arr[2] 10 11 12 13 14
arr[3] 15 16 17 18 19
arr[4] 20 21 22 23 24

21. for (i = 0; i < 5; i++) {
int *pb = arr[i];
for (j = 0; j < 5; j++) {
printf("%2d ", *pb);
pb++;
}
printf("n");
}

22. for (i = 0; i < 5; i++) {
for (j = 0; j < 5; j++)
printf("%2d ", *(*(arr + i) + j));
printf("n");
}
__________
+1 sizeof(int)*5
arr[0] 0 1 2 3 4
arr[1] 5 6 7 8 9
arr[2] 10 11 12 13 14
arr[3] 15 16 17 18 19
arr[4] 20 21 22 23 24

23. for (i = 0; i < 5; i++) {
for (j = 0; j < 5; j++)
printf("%2d ", *(*(arr + i) + j));
printf("n");
}
int (*)[5]
int (*p)[5]
+1 sizeof(int)*5
arr[0] 0 1 2 3 4
arr[1] 5 6 7 8 9
arr[2] 10 11 12 13 14
arr[3] 15 16 17 18 19
arr[4] 20 21 22 23 24

24. int (*pa)[5] = arr;
for (i = 0; i < 5; i++) {
int *pb = *pa;
for (j = 0; j < 5; j++) {
printf("%2d ", *pb);
pb++;
}
printf("n");
pa++;
}

25. int a = 20, b = 10, c = 30, i;
int *pArr[3] = {&a, &b, &c};
for (i = 0; i < 3; i++)
printf("%d ", *pArr[i]);