I have been programming for a number of years already. I have seen others introduce bugs, and I have also introduced (and solved!) many bugs while coding. Off-by-one, buffer-overflow, treating pointers as pointees, different behaviors or the same function (this is specially true for cross-platform applications), race conditions, deadlocks, threading issues. I think I have seen quite a few of the typical issues.
Yet recently I lost a lot of time to what I would call the most stupid C bug in my career so far, and probably ever.
I am porting a Unix-only application which uses tmpfile() to create temporary files:
else if (code == 200) { // Downloading whole file
/* Write new file (plus allow reading once we finish) */
g = fname ? fopen(fname, "w+") : tmpfile();
}
For some awkward reason, Microsoft decided their implementation of tmpfile() would create temporary files in C:\, which is totally broken for normal (non-Administrator) users, and even for Administrator users under Windows 7.
In addition to that, the application did not work due to another same-function-diffent-behavior problem.
To make sure I did not forget about the tmpfile() issue, I dutifully added a FIXME in the code:
else if (code == 200) { // Downloading whole file
/* Write new file (plus allow reading once we finish) */
// FIXME Win32 native version fails here because Microsoft's version of tmpfile() creates the file in C:\
g = fname ? fopen(fname, "w+") : tmpfile();
}