ex20250616 - rlawjdaks/ex20250310_first GitHub Wiki

#pragma warning(disable:4996)
#include <stdio.h>
int main() {
	FILE* fp;
	//1.파일 열기
	fp = fopen("myfile.txt", "wt");
	//2. 파일 읽고/쓰기
	printf("data : %s\n", "Hello");
	fprintf(stdout, "data : %s\n", "Hello");
	fprintf(fp, "data : %s\n", "Hello");
	//3. 파일 닫기
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
int main() {
	FILE* fp;
	int n = 100;
	double d = 5.56;

	fp = fopen("myfile.txt", "wt");
	fprintf(fp, "%d %g %d %g \n", n, d, n, d);
	fclose(fp);
} // 읽을 수 없음 ->바이너리 파일(ppt,dll), 읽을 수 있음 ->텍스트 파일

#pragma warning(disable:4996)
#include <stdio.h>
int main() {
	FILE* fp;
	int n = 100;
	double d = 5.56;

	fp = fopen("myfile.txt", "wt");
	fprintf(fp, "%d %g %d %g \n", n, d, n, d);
	fclose(fp); 

	fp = fopen("myfile.txt", "rt");
	int n1, n2;
	double d1, d2;
	fscanf(fp, "%d %lf %d %lf", &n1, &d1, &n2, &d2); // 8바이트 읽을 떄 %lf
	fclose(fp);

	printf("data: %d %d, %g, %g\n", n1, n2, d1, d2);
}

#pragma warning(disable:4996)
#include <stdio.h>
int main() {
	FILE* fp = NULL;

	fp = fopen("myfile.txt", "wt"); {
		int arr[10] = { 100,200,31,56,78,90,506 };
		for (int i = 0; i < 10; ++i)
			printf("%d : %d\n", i, arr[i]);
	}
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
int main() {
	FILE* fp = NULL;

	fp = fopen("myfile.txt", "wt"); {
		int arr[10] = { 100,200,31,56,78,90,506 };
		for (int i = 0; i < 10; ++i)
			fprintf(fp, "index:%d : data:%d\n", i, arr[i]);
	}
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
int main() {
	FILE* fp = NULL;

	fp = fopen("myfile.txt", "wb"); // 바이너리는 b
	{
		int n = 100;
		fwrite(&n, 4, 1, fp);
	}
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
int main() {
	FILE* fp = NULL;
	
	fp = fopen("myfile_text.txt", "wt");
	{
		int n = 12345678;
		fprintf(fp, "%d", n);
	}
	fclose(fp);

	fp = fopen("myfile_binary.txt", "wb");
	{
		int n = 12345678;
		fwrite(&n, 4, 1, fp);
	}
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
#include <string.h>
int main() {
	FILE* fp = NULL;
	
	fp = fopen("myfile.txt", "wb");
	{
		char type = 'I';
		int data = 100;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(int), 1, fp);
	}
	{
		char type = 'D';
		double data = 3.141592;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(double), 1, fp);
	}
	{
		char type = 'S';
		const char* data = "Hello";
		int slen = strlen(data)+1;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&slen, sizeof(int), 1, fp);
		fwrite(data, slen, 1, fp);
	}
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
#include <string.h>
int main() {
	FILE* fp = NULL;

	fp = fopen("myfile.txt", "wb");
	{
		char type = 'I';
		int data = 100;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(int), 1, fp);
	}
	{
		char type = 'D';
		double data = 3.141592;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(double), 1, fp);
	}
	{
		char type = 'S';
		const char* data = "Hello";
		int slen = strlen(data) + 1;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&slen, sizeof(int), 1, fp);
		fwrite(data, slen, 1, fp);
	}
	fclose(fp);
	//////////////////////////////
	fp = fopen("myfile.txt", "rb");
	{
		for (int i = 0; i < 3; ++i)
		{
			char type = 0;
			fread(&type, sizeof(char), 1, fp);
			switch (type)
			{
			case 'I': {
				int data = 0;
				fread(&data, sizeof(int), 1, fp);
				printf("int : %d\n", data);
			}
				break;
			case 'D': {
				double data = 0;
				fread(&data, sizeof(double), 1, fp);
				printf("double : %g\n", data);
			}
				break;
			case 'S': {
				char buf[1024] = { 0 };
				int slen = 0;
				fread(&slen, sizeof(int), 1, fp);
				fread(buf, slen, 1, fp);
				printf("string : %s\n", buf);
			}
				break;
			}
		}
	}
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
#include <string.h>
int main() {
	FILE* fp = NULL;

	fp = fopen("myfile.txt", "wb");
	{
		int dataLen = 3;
		fwrite(&dataLen, sizeof(int), 1, fp);
	}
	{
		char type = 'I';
		int data = 100;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(int), 1, fp);
	}
	{
		char type = 'D';
		double data = 3.141592;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(double), 1, fp);
	}
	{
		char type = 'S';
		const char* data = "Hello";
		int slen = strlen(data) + 1;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&slen, sizeof(int), 1, fp);
		fwrite(data, slen, 1, fp);
	}
	fclose(fp);
	//////////////////////////////
	fp = fopen("myfile.txt", "rb");
	int readLen = 0;
	{
		fread(&readLen, sizeof(int), 1, fp);
	}
	{
		for (int i = 0; i < readLen; ++i)
		{
			char type = 0;
			fread(&type, sizeof(char), 1, fp);
			switch (type)
			{
			case 'I': {
				int data = 0;
				fread(&data, sizeof(int), 1, fp);
				printf("int : %d\n", data);
			}
					break;
			case 'D': {
				double data = 0;
				fread(&data, sizeof(double), 1, fp);
				printf("double : %g\n", data);
			}
					break;
			case 'S': {
				char buf[1024] = { 0 };
				int slen = 0;
				fread(&slen, sizeof(int), 1, fp);
				fread(buf, slen, 1, fp);
				printf("string : %s\n", buf);
			}
					break;
			}
		}
	}
	fclose(fp);
}

#pragma warning(disable:4996)
#include <stdio.h>
#include <string.h>
int main() {
	FILE* fp = NULL;

	fp = fopen("myfile.txt", "wb");
	{
		int dataLen = 6;
		fwrite(&dataLen, sizeof(int), 1, fp);
	}
	///////
	{
		char type = 'D';
		double data = 2.998;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(double), 1, fp);
	}
	{
		char type = 'I';
		int data = 100;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(int), 1, fp);
	}
	{
		char type = 'D';
		double data = 3.141592;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(double), 1, fp);
	}
	{
		char type = 'S';
		const char* data = "Hello";
		int slen = strlen(data) + 1;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&slen, sizeof(int), 1, fp);
		fwrite(data, slen, 1, fp);
	}
	{
		char type = 'S';
		const char* data = "hong gil dong";
		int slen = strlen(data) + 1;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&slen, sizeof(int), 1, fp);
		fwrite(data, slen, 1, fp);
	}
	{
		char type = 'I';
		int data = 255;
		fwrite(&type, sizeof(char), 1, fp);
		fwrite(&data, sizeof(int), 1, fp);
	}
	fclose(fp);
	//////////////////////////////
	fp = fopen("myfile.txt", "rb");
	int readLen = 0;
	{
		fread(&readLen, sizeof(int), 1, fp);
	}
	{
		for (int i = 0; i < readLen; ++i)
		{
			char type = 0;
			fread(&type, sizeof(char), 1, fp);
			switch (type)
			{
			case 'I': {
				int data = 0;
				fread(&data, sizeof(int), 1, fp);
				printf("int : %d\n", data);
			}
					break;
			case 'D': {
				double data = 0;
				fread(&data, sizeof(double), 1, fp);
				printf("double : %g\n", data);
			}
					break;
			case 'S': {
				char buf[1024] = { 0 };
				int slen = 0;
				fread(&slen, sizeof(int), 1, fp);
				fread(buf, slen, 1, fp);
				printf("string : %s\n", buf);
			}
					break;
			}
		}
	}
	fclose(fp);
}