따라 배우는 C언어 : 14

🙇‍♀️14

🪐텍스트 파일 입출력 예제

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


int main(int argc, char* argv[])
{
	int ch;
	FILE* fr, *fw;	// TODO: file pointer to write

	const char* out_filename = "copy.txt";

	//typedef struct _iobuf
	//{
	//	char* _ptr;
	//	int _cnt;
	//	char* _base;
	//	int _flag;
	//	int _file;
	//	int _charbuf;
	//	int _bufsiz;
	//	char* _tmpfname;
	//}FILE;

	//const char* out_filename = "output.txt"; //TODO: Use this

	unsigned long count = 0;

	if (argc != 2)
	{
		printf("Usage: %s filename\n", argv[0]);
		exit(EXIT_FAILURE);
	}

	if ((fr = fopen(argv[1], "r")) == NULL) //Open a text file for reading
	{
		printf("Can't open %s\n", argv[1]);
		exit(EXIT_FAILURE);
	}

	if ((fw = fopen(out_filename, "w")) == NULL) //Open a text file for writing.
	{
		printf("Can't open %s\n", out_filename);
		exit(EXIT_FAILURE);
	}

	/*
		fopen mode strings for text files
		- r: reading
		- w: creating-and-writing or over-writing
		- a: appending or creating-and-writing
		- r+: both reading and writing
		- w+: reading and writing, over-writing or creating
		- a+: reading and writing, appending or creating
	*/

	// TODO: open file to write with "w" mode string

	while ((ch = fgetc(fr)) != EOF) // getc(fr)
	{
		//putc(ch, stdout); // same as putchar(ch);
		fputc(ch, stdout);

		//TODO: use fputs() to write a file stream!
		fputc(ch, fw);

		count++;
	}

	fclose(fr);
	fclose(fw);
	// TODO:

	printf("FILE %s has %lu characters\n", argv[1], count);
	printf("Copied to %s", out_filename);

	return 0;
}