File truncate and padding in C

Question

How can I truncate a file with the given size and if the filesize is smaller then the given size how can I enlarge the existing file size with 0 padding.

Thanks for the help.

Not a real dupes, as this question is about resizing a file in general, not only about shrinking. — alk, Aug 21 '13 at 06:17

alk · Answer 1 · 2013-08-21T06:18:35.607

1

To skrink use truncate() or ftruncate(), to enlarge use lseek()/fseek() followed by write()/fwrite()ing one byte.

edited Aug 21 '13 at 06:18

answered Aug 21 '13 at 06:13

alk

69,737
10
105
255

Is there any other way to enlarge the size. – user503403 Aug 21 '13 at 06:43
@user503403: Without (seeking and) writing? No. – alk Aug 21 '13 at 07:36

score 0 · Answer 2 · edited May 23 '17 at 11:56

0

This may help you with truncation:

How to truncate a file in C?

And I do not think you can enlarge a file without some kind of padding (it depends on how you view "padding").

edited May 23 '17 at 11:56

Community

1
1

answered Aug 21 '13 at 06:08

Joohwan

2,374
1
19
30

score 0 · Answer 3 · edited May 23 '17 at 11:49

0

It has been solved in this How to truncate a file in C?
Basically, you can use these two functions:

#include <unistd.h>
int ftruncate(int fildes, off_t length);
int truncate(const char *path, off_t length);

edited May 23 '17 at 11:49

Community

1
1

answered Aug 21 '13 at 06:16

Jin Chen

632
1
4
10

File truncate and padding in C

3 Answers3