Perfect C 3판 Chapter 11. Programming practice

01.

#include <stdio.h>

int main(void)
{
	int data = 100;

	printf("%d %p\n", data, &data);

	return 0;
}

02.

#include <stdio.h>

int main(void)
{
	int a[5] = { 1,2,3,4,5 };
	int* p;
	p = &a[2];

	printf("%d %d %d %d %d\n", p[-2], p[-1], p[0], p[1], p[2]);
	printf("%d %d %d %d %d\n", *(p - 2), *(p - 1), *p, *(p + 1), *(p + 2));

	return;
}

03.

#include <stdio.h>

int main(void)
{
	double a[] = { 3.4, 2.2, 1.5, 2.8 };
	double* p = a;

	int size = sizeof(a) / sizeof(a[0]);
	
	int minIndex = 0;

	for (int i = 1; i < size; i++)
	{
		if (*(p + i) < *(p + minIndex))
			minIndex = i;
	}
	printf("최소 값, 첨자: %d 값: %.1lf\n", minIndex, *(p + minIndex));

	return 0;
}

04.

#include <stdio.h>

int main(void)
{
	int value = 0x000000FF;
	int* pi = &value;

	printf("%d\n", *pi);

	short* ps = (short*)&value;
	*(ps + 1) = 0x000F;
	printf("%d %d", *ps, *(ps + 1));

	return 0;
}

05.

#include <stdio.h>

int main(void)
{
	int arr[3][4] = {
		{11,22,33,44},
		{55,66,77,88},
		{11,66,77,44} };

	int(*p)[4] = arr;

	for (int i = 0; i < 3; i++)
	{
		for (int j = 0; j < 4; j++) {
			printf("arr[%d][%d] = %d  ", i, j, *(*(p + i) + j)); // *(p[i] + j)
		}
		puts("");
	}
	return 0;
}

06.

#include <stdio.h>

int main(void)
{
	int a[3][5] = {
		{1,2,3,4,5},
		{10,20,30,40,50},
		{100,200,300,400,500} };

	int* p[3] = { a[0],a[1],a[2] };

	for (int i = 0; i < 3; i++) {
		for (int j = 0; j < 5; j++) {
			printf("a[%d][%d] = %3d  ", i, j, *(p[i] + j));
		}
		puts("");
	}
	return 0;
}

07.

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main(void)
{
	double split = 0;
	int* p1 = (int*)&split;
	int* p2 = p1 + 1;
	printf("두 정수 입력: ");
	scanf("%d %d", p1, p2);


	printf("%d + %d = %d\n", *p1, *p2, *p1 + *p2);
	printf("%d - %d = %d\n", *p1, *p2, *p1 - *p2);
	printf("%d * %d = %d\n", *p1, *p2, *p1 * *p2);
	printf("%d %% %d = %d\n", *p1, *p2, *p1 % *p2);

	return 0;
}

08.

#include <stdio.h>

int main(void)
{
	int a[] = { 11,22,33,44,55,66 };
	int* p = a;
	int* q = a + 5;

	while (p < q) {
		int temp = *p;
		*p = *q;
		*q = temp;
		/* XOR SWAP 
		*p ^= *q;
		*q ^= *p;
		*p ^= *q;
		*/
		p++;
		q--;
	}

	// 역으로 바뀐 배열 출력
	for (int i = 0; i < 6; i++) {
		printf("%d ", a[i]);
	}
	puts("");

	return 0;
}