C언어(6)

2025.02.25

 

함수포인터

 

메모리 동적 할당

 

 

사용자 정의 자료형

 

파일 입출력

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main(int argc, char** argv) {
	int i;
	/*for (i = 0; i < argc; i++)
	{
		printf("%s\n", argv[i]);
	}*/

	/*while (*argv != NULL)
	{
		printf("%s\n", *argv);
		argv++;
	}*/

	app();
}

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

/*
void app() {
	int** matrix;
	// 4개의 행 공간의 할당
	matrix = (int**)malloc(4 * sizeof(int*));
	// 5개의 열 공간의 할당
	for (int i = 0; i < 4; i++)
	{
		matrix[i] = (int*)malloc(5 * sizeof(int));
	}
	// 값 대입
	for (int y = 0; y < 4; y++)
	{
		for (int x = 0; x < 5; x++)
		{
			matrix[y][x] = (y + 1) * 10 + (x + 1);
		}
	}
	// 값 인쇄
	for (int y = 0; y < 4; y++)
	{
		for (int x = 0; x < 5; x++)
		{
			printf("%5d", matrix[y][x]);
		}
		printf("\n");
	}
	// 공간 반환
	for (int y = 0; y < 4; y++)
	{
		free(matrix[y]);
	}
	free(matrix);
}
*/

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

/*
// 구조체 선언 (명시적)
struct student
{
	int num;
	double grade;
};
// 구조체 선언 (암시적)
typedef struct{
	int num;
	double grade;
} student2_t;

void app() {
	struct student s1; // 구조체를 사용한 변수 선언
	student2_t s2;

	s1.num = 2;
	s1.grade = 2.7;
	printf("학번 : %d\n", s1.num);
	printf("학점 : %.1lf\n", s1.grade);

	return 0;
}
*/

/*
struct profile
{
	char name[20];
	int age;
	double height;
	char* intro;
};

void app() {
	struct profile yuni;

	strcpy(yuni.name, "서하윤");
	yuni.age = 17;
	yuni.height = 164.5;

	yuni.intro = (char*)malloc(80);
	printf("자기소개 : ");
	gets(yuni.intro);

	printf("이름 : %s\n", yuni.name);
	printf("나이 : %d\n", yuni.age);
	printf("키 : %.1lf\n", yuni.height);
	printf("자기소개 : %s\n", yuni.intro);
	free(yuni.intro);

	return 0;
}*/

/*
struct profile
{
	int age;
	double height;
};

struct student
{
	struct profile pf;
	int id;
	double grade;
};

void app() {
	struct student yuni;

	yuni.pf.age = 17;
	yuni.pf.height = 164.5;
	yuni.id = 315;
	yuni.grade = 4.3;

	printf("나이 : %d\n", yuni.pf.age);
	printf("키 : %.1lf\n", yuni.pf.height);
	printf("학번 : %d\n", yuni.id);
	printf("학점 : %.1lf\n", yuni.grade);

	return 0;
}*/

/*
struct student
{
	int id;
	char name[20];
	double grade;
};

void app() {
	struct student s1 = { 315, "홍길동", 2.4 },
		s2 = { 316, "이순신", 3.7 },
		s3 = { 317, "세종대왕", 4.4 };

	struct student max;

	max = s1;
	if (s2.grade > max.grade) max = s2;
	if (s3.grade > max.grade) max = s3;

	printf("학번 : %d\n", max.id);
	printf("이름 : %s\n", max.name);
	printf("학점 : %.1lf\n", max.grade);

	return 0;
}*/

/*
struct student
{
	int id;
	char name[20];
	double grade;
}s1 = { 315, "홍길동", 2.4 },
s2 = { 316, "이순신", 3.7 },
s3 = { 317, "세종대왕", 4.4 };

void app() {
	struct student max;

	max = s1;
	if (s2.grade > max.grade) max = s2;
	if (s3.grade > max.grade) max = s3;

	printf("학번 : %d\n", max.id);
	printf("이름 : %s\n", max.name);
	printf("학점 : %.1lf\n", max.grade);

	return 0;
}*/

/*
struct vision
{
	double left;
	double right;
};

struct vision exchange(struct vision robot);

void app() {
	struct vision robot;

	printf("시력 입력 : ");
	scanf("%lf%lf", &(robot.left), &(robot.right));
	robot = exchange(robot);
	printf("바뀐 시력 : %.1lf %.1lf\n", robot.left, robot.right);

	return 0;
}

struct vision exchange(struct vision robot)
{
	double temp;

	temp = robot.left;
	robot.left = robot.right;
	robot.right = temp;

	return robot;
}*/

/*
struct book
{
	char title[20];
	char author[20];
	int page;
	double price;
};*/

/*
struct cracker
{
	int price;
	int calories;
};

void app() {
	struct cracker c;

	printf("바사삭의 가격과 열량을 입력하세요 : ");
	scanf("%d %d", &c.price, &c.calories);
	printf("바사삭의 가격 : %d원\n", c.price);
	printf("바사삭의 열량 : %dkcal\n", c.calories);

	return 0;
}*/

/*
struct score
{
	int kor;
	int eng;
	int math;
};

void app() {
	struct score yuni = { 90, 80, 70 };
	struct score* ps = &yuni;

	printf("국어 : %d\n", (*ps).kor);
	printf("영어 : %d\n", ps->eng);
	printf("수학 : %d\n", ps->math);

	return 0;
}*/

/*
struct address
{
	char name[20];
	int age;
	char tel[20];
	char addr[80];
};

void app() {
	struct address list[5] = {
		{"홍길동", 23, "111-1111", "울릉도 독도"},
		{"이순신", 35, "222-2222", "서울 건천동"},
		{"장보고", 19, "333-3333", "완도 청해진"},
		{"유관순", 15, "444-4444", "충남 천안"},
		{"안중근", 45, "555-5555", "황해도 해주"}
	};
	struct address* list;
	// list = malloc(5 * sizeof(struct address));

	int i;

	for (i = 0; i < 5; i++)
	{
		printf("%10s%5d%15s%20s\n", list[i].name, list[i].age, list[i].tel, list[i].addr);
	}

	return 0;
}
*/

/*
struct address
{
	char name[20];
	int age;
	char tel[20];
	char addr[80];
};

void print_list(struct address* lp);

void app() {
	struct address list[5] = {
		{"홍길동", 23, "111-1111", "울릉도 독도"},
		{"이순신", 35, "222-2222", "서울 건천동"},
		{"장보고", 19, "333-3333", "완도 청해진"},
		{"유관순", 15, "444-4444", "충남 천안"},
		{"안중근", 45, "555-5555", "황해도 해주"}
	};
	
	print_list(list);

	return 0;
}

void print_list(struct address* lp)
{
	int i;

	for (i = 0; i < 5; i++)
	{
		printf("%10s%5d%15s%20s\n", (lp + i)->name, (lp + i)->age, (lp + i)->tel, (lp + i)->addr);
	}
}*/

/*
struct list
{
	int num;
	struct list* next;
};

void app() {
	struct list a = { 10, 0 }, b = { 20, 0 }, c = { 30, 0 };
	struct list* head = &a, * current;

	a.next = &b;
	b.next = &c;

	printf("head->num : %d\n", head->num);
	printf("head->next->num : %d\n", head->next->num);

	printf("list all : ");
	current = head;
	while (current != NULL)
	{
		printf("%d  ", current->num);
		current = current->next;
	}
	printf("\n");

	struct list bc = { 25, 0 };
	bc.next = b.next;
	b.next = &bc;

	printf("after added value : ");
	current = head;
	while (current != NULL)
	{
		printf("%d  ", current->num);
		current = current->next;
	}

	printf("\n");

	a.next = b.next;

	printf("after delete value : ");
	current = head;
	while (current != NULL)
	{
		printf("%d  ", current->num);
		current = current->next;
	}

	printf("\n");

	return 0;
}*/

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

/*
union student {
	int num;
	short num2;
	unsigned char num3;
	double grade;
};

void app() {
	union student s1 = { 0x123456 };

	printf("num : %x\n", s1.num);
	printf("grade : %.1lf\n", s1.grade);
	printf("num2 : %x\n", s1.num2);
	printf("num3 : %x\n", s1.num3);

	return 0;
}*/

/*
enum season
{
	SPRING, // 0
	SUMMER, // 1
	FALL,   // 2
	WINTER  // 3
};

void app() {
	enum season ss;
	char* pc = NULL;

	ss = 0;
	switch (ss)
	{
	case SPRING: pc = "inline"; break;
	case SUMMER: pc = "swimming"; break;
	case FALL: pc = "trip"; break;
	case WINTER: pc = "skiing"; break;
	}
	printf("나의 레저 활동 : %s\n", pc);
}
*/

/*
enum season
{
	SPRING = 100, // 100
	SUMMER,       // 101
	FALL,         // 102
	WINTER        // 103
};

void app() {
	enum season ss;
	char* pc = NULL;

	ss = 102;
	switch (ss)
	{
	case SPRING: pc = "inline"; break;
	case SUMMER: pc = "swimming"; break;
	case FALL: pc = "trip"; break;
	case WINTER: pc = "skiing"; break;
	}
	printf("나의 레저 활동 : %s\n", pc);
}
*/

/*
struct student
{
	int num;
	double grade;
};

typedef struct student Student;
void print_data(Student* ps);

void app() {
	Student s1 = { 315, 4.2 };

	print_data(&s1);

	return 0;
}

void print_data(Student* ps) {
	printf("학번 : %d\n", ps->num);
	printf("학점 : %.1lf\n", ps->grade);
}*/

/*
struct marriage
{
	char name[20];
	int age;
	char gender;
	double height;
};

void app() {
	struct marriage m1 = { "Andy", 22, 'm', 187.5};
	struct marriage* mp = &m1;

	printf("이름 : %s\n", mp->name);
	printf("나이 : %d\n", (*mp).age);
	printf("성별 : %c\n", mp->gender);
	printf("키 : %.1lf\n", mp->height);
}*/

/*
typedef struct train Train;

struct train
{
	int seats;
	Train* next;
};

void app() {
	Train* head = NULL, * tail = NULL;
	int i;
	// 연결고리 생성
	for (i = 0; i < 5; i++)
	{
		if (head == NULL)
		{
			head = tail = (Train*)malloc(sizeof(Train));
		}
		else
		{
			tail->next = (Train*)malloc(sizeof(Train));
			tail = tail->next;
		}
	}
	// 연결고리에 값을 대입
	head->seats = 1;
	head->next->seats = 2;
	head->next->next->seats = 3;
	head->next->next->next->seats = 4;
	head->next->next->next->next->seats = 5;
	// 연결고리 값을 인쇄
	Train *current;
	current = head;
	while (current != NULL)
	{
		printf("%d  ", current->seats);
		current = current->next;
	}
}
*/

/*
typedef enum { CYAN, MAGENTA, YELLOW = 5, BLACK } COLOR;
typedef enum { UP, DOWN, LEFT, RIGHT } ARROW;

void app() {
	COLOR my_color = YELLOW, c;
	ARROW direction = UP;

	for (c = CYAN; c <= BLACK; c++)
	{
		direction++;
		direction = direction % 4;
		if (c == my_color) break;
	}

	switch (direction)
	{
	case UP: printf("현재 방향 : 위"); break;
	case DOWN: printf("현재 방향 : 아래"); break;
	case LEFT: printf("현재 방향 : 왼쪽"); break;
	case RIGHT: printf("현재 방향 : 오른쪽"); break;
	}
	return 0;
}*/

/*
void app() {
	FILE* fp;

	fp = fopen("c:\\Users\\microsoft\\source\\repos\\structure\\x64\\Debug\\a.txt", "r");
	if (fp == NULL)
	{
		printf("파일이 열리지 않았습니다.\n");
		return;
	}
	printf("파일이 열렸습니다.\n");
	// 내용 읽기
	for (int i = 0; i < 11; i++)
	{
		char ch = fgetc(fp);
		printf("%c", ch);
	}
	
	fclose(fp);

	return 0;
}
*/

void app() {
	FILE* fp;

	fp = fopen("c:\\Users\\microsoft\\source\\repos\\structure\\x64\\Debug\\a.txt", "r");
	if (fp == NULL)
	{
		printf("파일이 열리지 않았습니다.\n");
		return;
	}
	printf("파일이 열렸습니다.\n");
	// 내용 읽기
	//while (1)
	//{
	//	char ch = fgetc(fp);
	//	if (ch == EOF) break; // End Of File
	//	printf("%c", ch);
	//}
	char line[80];
	int count;
	fread(line, 1, 80, fp);
	printf("%s\n", line);

	fclose(fp);

	return 0;
}

0225.c

0.00MB

structure.c

0.00MB

file.c

0.00MB

typedef.c

0.01MB