o_195h4n6al16jb186b1b2qs7fgssa.pdf

*mode, FILE *stream);
Arguments: filename name of the new file
mode type of access permitted
stream pointer to the currently open stream
Return Value: Returns a pointer to the new open file. If the function fails a null
pointer
is returned.
Remarks: The function closes the file associated with the stream as though
fclosewas called. Then it opens the new file as though fopenwas
called. freopenwill fail if the specified stream is not open. See fopen
for the possible types of file access.
Example: #include /* for fopen, freopen, */
/* printf, fclose, */
/* FILE, NULL */
int main(void)
{
FILE *myfile1, *myfile2;
int y;
if ((myfile1 = fopen("afile1", "w+")) == NULL)
printf("Cannot open afile1\n");
else
{
printf("afile1 was opened\n");
if ((myfile2 = freopen("afile2", "w+",
myfile1)) == NULL)
{
printf("Cannot open afile2\n");
fclose(myfile1);
}
else
{
printf("afile2 was opened\n");
fclose(myfile2);
}
}
}
Output:
afile1 was opened
afile2 was opened
FILE * myfile;
char s [70];
int y;
myfile = fopen ("afile.out", "w +");
if (myfile == NULL)
printf ("Không thể mở afile.out \ n");
khác
{
fprintf (myfile, "Đây là sự khởi đầu"
"Đây là trung bình và"
"Đây là kết thúc.");
y = fseek (myfile, 0l, SEEK_SET);
if (y)
perror ("fseek thất bại");
khác
{
fgets (s, 22, myfile);
printf ("\"% s \ "\ n \ n", s);
}
y = fseek (myfile, 2L, SEEK_CUR);
if (y)
perror ("fseek thất bại");
khác
{
fgets (s, 70, myfile);
printf ("\"% s \ "\ n \ n", s);
}
Thư viện chuẩn C với hàm toán học
2004 Microchip Technology Inc DS51456B trang 245
y = fseek (myfile, -16L, SEEK_END);
if (y)
perror ("fseek thất bại");
khác
{
fgets (s, 70, myfile);
printf ("\"% s \ "\ n", s);
}
fclose (myfile);
}