/* append.c -- appends files to a file */
#include
#include
#include
#define BUFSIZE 4096
#define SLEN 81
//13.11-5.exe abc.txt def.txt
void append(FILE *source, FILE *dest);
char * s_gets(char * st, int n);
int main (int argc, char *argv[] )
{
FILE *fa, *fs; // fa for append file, fs for source file
int files = 0; // number of files appended
int ch;
if (argc < 3)
exit(EXIT_FAILURE);
else
{
if ((fa = fopen(argv[1], "a+")) == NULL)
{
fprintf(stderr, "Can't open %s\n", argv[1]);
exit(EXIT_FAILURE);
}
if (setvbuf(fa, NULL, _IOFBF, BUFSIZE) != 0)
{
fputs("Can't create output buffer\n", stderr);
exit(EXIT_FAILURE);
}
if (strcmp(argv[2], argv[1]) == 0)
fputs("Can't append file to itself\n",stderr);
else if ((fs = fopen(argv[2], "r")) == NULL)
fprintf(stderr, "Can't open %s\n", argv[2]);
else
{
if (setvbuf(fs, NULL, _IOFBF, BUFSIZE) != 0)
//要知道,在打开fs的时候,C标准库会为该文件流自动分配一个缓冲区,并采用默认的缓冲策略。如果我们不希望默认的策略,采用setvbuf去修改.
fputs("Can't create input buffer\n",stderr);
append(fs, fa);
if (ferror(fs) != 0)
fprintf(stderr,"Error in reading file %s.\n",
argv[2]);
if (ferror(fa) != 0)
fprintf(stderr,"Error in writing file %s.\n",
argv[1]);
fclose(fs);
files++;
printf("Done appending. %d files appended.\n", files);
rewind(fa);
printf("%s contents:\n", argv[1]);
while ((ch = getc(fa)) != EOF)
putchar(ch);
puts("\nDone displaying.");
fclose(fa);
}
}
return 0;
}
void append(FILE *source, FILE *dest)
{
size_t bytes;
static char temp[BUFSIZE]; // allocate once
while ((bytes = fread(temp,sizeof(char),BUFSIZE,source)) > 0)
fwrite(temp, sizeof (char), bytes, dest);
}