如何删除不带文件名的文件内容？

Question

I have a function that takes in a file pointer ( FILE * file ) and copies everything in that file. Now, is it possible to erase everything inside this file?

I do not have the file name so I can not use fopen(filename, "w") again.

I have stdio.h and string.h included.

Answer 1

You can use the ftruncate() system call to empty a file using its file descriptor, eg

ftruncate(fileno(fh), 0);

You will probably want to follow that up with a call to rewind(fh) so that any further writes to the file are made at the beginning, rather than at the previous offset.