getline函数实现 2020-12-29

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

int mygetline(char **lineptr, int *n, FILE *fp)
{
	if(*lineptr == NULL)
	{
		*lineptr = (char *)malloc(10);
		*n += 10;
	}
	char c = 0;
	int count = 0;
	while((c = fgetc(fp)) != EOF)
	{
		if(c == '\n')
		{
			break;
		}else
		{
			(*lineptr)[count] = c;
			count++;
		}
		if(count == *n - 1)
		{
			*n += 10;
			*lineptr = realloc(*lineptr, *n);
		}
	}
	(*lineptr)[count] = '\0';
	return count;
}

int main ()
{
	FILE *fp = fopen("b.txt", "r+");//判断是否为空
	FILE *fp1 = fopen("c.txt", "w+");
	char *line = NULL;
	int n = 0;
	mygetline(&line, &n, fp);

	int len = strlen(line);
	fwrite(line, len, 1, fp1);

	close(fp);
	close(fp1);
	if(line)
	{
		free(line);
		line = NULL;
	}
	return 0;
}