Mar 19, 2018 · ftruncate() is also a standard POSIX function and is portable. Note that POSIX does not specify how an OS sets the file length, such as whether or not a file set to any length is a sparse file . fallocate() is a Linux-specific function that does a lot more, and in very specific ways:

Nov 7, 2014 · I want to use ftruncate function in my code. I have to compile with option std=c99. I get warning: In function ‘test’: warning: implicit declaration of function ‘ftruncate’ [-Wimplicit-function-declaration] I tied to find on the Internet any solution which can solve this problem but I don't succeeded in.

Mar 26, 2018 · For more information, see ftruncate(3). However, it might be the case that you are confused because you are trying to use a POSIX function instead of C or C++ standard ones. If so, check out How to truncate a file in C? and similar questions for solutions that rely only on the C or C++ standards.

I'm using C to write some data to a file. I want to erase the previous text written in the file in case it was longer than what I'm writing now. I want to decrease the size of file or truncate unti...

Dec 7, 2012 · Note that ftruncate() operates on a POSIX file descriptor (despite its potentially misleading name), not a STDIO stream FILE handle. Note also that mixing operations on the STDIO stream and on the underlying OS calls which operate on the file descriptor for the open stream can confuse the internal runtime state of the STDIO library.

Nov 12, 2013 · Just #define ftruncate _chsize_s. (Use _chsize_s() with a 64-bit offset parameter, as opposed to _chsize() ...

Oct 12, 2016 · Under Unix, this is ftruncate. But you'll need to find the byte count where you want to truncate first; ftruncate requires an open file, but it won't truncate at the current position in the file. So you'll have to 1) find the start of this last line in the file, 2) seek to it, 3) write the new value, 4) call ftell (or ftello , if the length can ...

Sep 12, 2017 · man ftruncate tells me that you need. #include <unistd.h> #include <sys/types.h> Try including these before including boost interprocess headers. If then still it fails to recognize these functions, clearly Cygwin does not support those …

I ran npm config set prefix /usr/local After running that command, When trying to run any npm commands on Windows OS I keep getting the below. Error: EPERM: operation not permitted, mkdir 'C:\\Prog...

Sep 28, 2011 · Use ftruncate to truncate your file, it just requires the file descriptor and a size. Then later you can use fstat to query the properties of the underlying file and use the size you obtain from there to dimension future mappings.