/*CPP 程序清单13.6*/
/*重写: 使用命令行参数获得文件名*/
/*
参数1为目标文件,其他参数为源文件 
依次打开源文件将内容追加到目标文件中
如果源文件打不开,则跳过此文件打开下一个源文件 

*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define BUFSIZE 1024
#define SIZE 40

void append(FILE *, FILE *);

int main(int argc, char **argv)
{
	char tgt_file[SIZE];
	char src_file[SIZE];
	FILE * fpt, * fps;
	int i, files = 0;
	
	if(argc < 2)
	{
		fprintf(stderr, "Wrong number of parameters!\n");
		exit(1);
	}
	
	strcpy(tgt_file, argv[1]);
	
	if((fpt = fopen(tgt_file, "a")) == NULL)		/*如果目标文件打开或创建失败,则退出程序*/
	{
		fprintf(stderr, "Can't open file %s.\n", tgt_file);
		exit(1);
	}
	if(setvbuf(fpt, NULL, _IOFBF, BUFSIZE) != 0)	/*创建目标文件缓冲区*/
	{
		fprintf(stderr, "Can't create output buffer.\n");
		exit(2);
	}
	
	for(i = 2; i < argc; i++)
	{
		strcpy(src_file, argv[i]);
		if(strcmp(tgt_file, src_file) == 0)				/*同名文件不能追加*/
		{
			fprintf(stderr, "Cannot append to itself!\n");
			continue;
		}
		
		if((fps = fopen(src_file, "r")) == NULL)
		{
			fprintf(stderr, "Can't open file %s.\n", src_file);
			continue;
		}
		append(fpt, fps);
			
		fclose(fps);
		files++;
	}
	fclose(fpt);
	fprintf(stdout, "Done. %d files appended.\n", files);
	return 0;
}

void append(FILE *fpt, FILE * fps)
{
	size_t bytes;
	static char temp[BUFSIZE];
	
	while((bytes = fread(temp, sizeof(char), BUFSIZE, fps)))
		fwrite(temp, sizeof(char), bytes, fpt);
}