Perfect C 3판 Chapter 16. Programming practice

01.

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
	int input;
	printf("입력할 실수의 갯수를 입력 >> ");
	scanf("%d", &input);

	double* dynable = (double*)malloc(sizeof(double) * input);
	if (dynable == NULL) {
		printf("메모리 할당에 문제가 있습니다.\n");
		exit(1);
	}
	printf("%d개의 실수 입력 >> ", input);
	for (int i = 0; i < input; i++)
	{
		scanf("%lf", (dynable + i));
	}
	printf("입력한 실수\n");
	for (int i = 0; i < input; i++)
	{
		printf("%.2lf ", *(dynable + i));
	}

	free(dynable);
	return 0;
}

02.

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

struct point {
	double x;
	double y;
};

struct circle {
	struct point point;
	double radius;
};

int main(void)
{
	struct circle* mycircle = (struct circle*)malloc(sizeof(struct circle));

	if (mycircle == NULL) {
		printf("구조체 메모리 할당에 문제가 있습니다.\n");
	}

	mycircle->point.x = 1.24;
	mycircle->point.y = 3.82;
	mycircle->radius = 4.93;

	printf("원 중심좌표(%.2lf, %.2lf), 반지름: %.2lf\n", mycircle->point.x, mycircle->point.y, mycircle->radius);
	printf("원면적: %.2lf\n", 3.14 * 3.14 * mycircle->radius);

	free(mycircle);
	return 0;
}

03.

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

typedef struct node {
	int cnt;
	char name[20];
	double middle;
	double final;
	struct node* next;
}node;

node* createNode(int, char*, double, double);

int main(void)
{
	FILE* fp;

	if (fopen_s(&fp, "input.txt", "r") != 0) {
		printf("파일을 여는데 문제가 생겼습니다.\n");
		exit(1);
	}

	char buff[50];
	int cnt;
	char name[20];
	double middle;
	double final;	

	node* head = NULL;
	node* cur;
	while (fgets(buff, 50, fp) != NULL) {
	//while (fscanf_s(fp, "%d %s %lf %lf", &cnt, name, 20, &middle, &final) == 4) { 해도 됨, 이렇게 하면 buff에 저장 할 필요도 없고 좋네..
		sscanf_s(buff, "%d %s %lf %lf", &cnt, name, 20, &middle, &final);

		if (head == NULL) {
			head = createNode(cnt, name, middle, final);
			cur = head;
		}
		else {
			cur = head;
			while (cur->next != NULL)
			{
				cur = cur->next;
			}
			cur->next = createNode(cnt, name, middle, final);
		}
	}

	//순회하면서 프린트하고 free해 줌
	cur = head;
	while (cur != NULL) {
		node* deletion = cur;
		printf("%8d %10s %10.1lf %10.1lf %10.1lf\n", cur->cnt, cur->name, cur->middle, cur->final, (cur->middle + cur->final));
		cur = cur->next;
		free(deletion);
	}

	fclose(fp);
	return 0;
}

node* createNode(int count, char* name, double mid, double fin)
{
	node* cur = (node*)malloc(sizeof(node));
	if (cur == NULL) {
		printf("동적 메모리 할당에 실패했습니다.\n");
		exit(1);
	}
	cur->cnt = count;
	strcpy(cur->name, name);
	cur->middle = mid;
	cur->final = fin;
	cur->next = NULL;
	
	return cur;
}

04.

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

typedef struct node {
	int cnt;
	char name[20];
	double middle;
	double final;
	struct node* next;
}node;

node* createNode(int, char*, double, double);

int main(void)
{
	FILE* fp;

	if (fopen_s(&fp, "input.txt", "r") != 0) {
		printf("파일을 여는데 문제가 생겼습니다.\n");
		exit(1);
	}

	int cnt;
	char name[20];
	double middle;
	double final;

	node* head = NULL;
	node* cur;
	while (fscanf_s(fp, "%d %s %lf %lf", &cnt, name, 20, &middle, &final) == 4) {
		if (head == NULL) {
			head = createNode(cnt, name, middle, final);
			cur = head;
		}
		else {
			cur = head;
			while (cur->next != NULL)
			{
				cur = cur->next;
			}
			cur->next = createNode(cnt, name, middle, final);
		}
	}

	fclose(fp);

	FILE* fp2;
	if (fopen_s(&fp2, "out.txt", "w") != 0) {
		printf("파일을 여는데 문제가 생겼습니다.\n");
		exit(1);
	}

	//순회하면서 프린트하고 free해 줌
	cur = head;
	while (cur != NULL) {
		node* deletion = cur;
		printf("%8d %10s %10.1lf %10.1lf %10.1lf\n", cur->cnt, cur->name, cur->middle, cur->final, (cur->middle + cur->final));
		fprintf(fp2,"%8d %10s %10.1lf %10.1lf %10.1lf\n", cur->cnt, cur->name, cur->middle, cur->final, (cur->middle + cur->final));
		cur = cur->next;
		free(deletion);
	}

	fclose(fp2);
	return 0;
}

node* createNode(int count, char* name, double mid, double fin)
{
	node* cur = (node*)malloc(sizeof(node));
	if (cur == NULL) {
		printf("동적 메모리 할당에 실패했습니다.\n");
		exit(1);
	}
	cur->cnt = count;
	strcpy(cur->name, name);
	cur->middle = mid;
	cur->final = fin;
	cur->next = NULL;

	return cur;
}

05.

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

void swap(int* a, int* b) {
	int temp = *a;
	*a = *b;
	*b = temp;
}

int main(void) {
	srand((long)time(NULL));

	int* ary = (int*)malloc(sizeof(int) * 10);
	if (ary == NULL) {
		printf("메모리 할당에 문제 발생\n");
		exit(1);
	}
	printf("정렬 전 배열값: -->\n");
	for (int i = 0; i < 10; i++) {
		*(ary + i) = rand() % 101;
		printf("%d",ary[i]);
		if (i != 9)
			printf(", ");
		else
			printf("\n");
	}
	//sequential sort
	for (int i = 0; i < 10; i++) {
		for (int j = 1 + i; j < 10; j++) {
			if (ary[i] > ary[j])
				swap(&ary[i], &ary[j]);
		}
	}

	printf("정렬 후 배열값: -->\n");
	for (int i = 0; i < 10; i++) {
		printf("%d", ary[i]);
		if (i != 9)
			printf(", ");
		else
			printf("\n");
	}
	free(ary);
	return 0;
}

 

06.

#include <stdio.h>
#define print(exp) printf(#exp" = %d\n", exp)

int main(void)
{
	int a = 2;
	print(3 * 4 + 3 / a);

	return 0;
}

07.

#include <stdio.h>
#define print(x, y) printf(#x "와 " #y"의 곱은 %d 입니다.\n",x*y)

int main(void)
{
	int a = 7, b = 2;
	print(a, b);

	return 0;
}

08.

#include <stdio.h>
#define PRINTMAX(a,b) printf(#a"와 "#b"의 최대값: %d\n", a>b?a:b)

int main(void)
{
	int a = 6, b = 5;
	PRINTMAX(a++, b);

	return 0;
}