The strtol declaration in stdio.h is as follows: long int strtol(const char *nptr, char **endptr, int base); strtol provides a robust error checking and validation scheme that allows you to determine whether the value returned is valid or invalid. Essentially, you have 3 primary tools at your disposal. (1) the value returned, (2) the value … Read more
scanf (and cousins) have one slightly strange characteristic: white space in (most placed in) the format string matches an arbitrary amount of white space in the input. As it happens, at least in the default “C” locale, a new-line is classified as white space. This means the trailing ‘\n’ is trying to match not only … Read more
The approach you’ve outlined is roughly correct, although you should use offsetof instead of attempting to figure out the offset on your own. I’m not sure why you mention memset — it sets the contents of a block to a specified value, which seems quite unrelated to the question at hand. Here’s some code to … Read more
The C standard does not allow to cast function pointers to void*. You may only cast to another function pointer type. In the C11 standard, 6.3.2.3 ยง8: A pointer to a function of one type may be converted to a pointer to a function of another type and back again Importantly, you must cast back … Read more
I think you first have to look through the open fds in /proc/*/fd, e.g. 4 -> socket:[11147] and then look for the referenced sockets (by the inode) in /proc/net/tcp (or /proc/net/udp), e.g. 12: B382595D:8B40 D5C43B45:0050 01 00000000:00000000 00:00000000 00000000 1000 0 11065 1 ffff88008bd35480 69 4 12 4 -1
You can create initializer functions that take a pointer to a structure. This was common practice. Also functions that create a struct and initialize it (like a factory) – so there is never a time where the struct is “uninitialized” in the “client” code. Of course – that assumes people follow the convention and use … Read more
C Preprocessor works top to bottom irrespective of function calls. It is effective from that point (line) in whatever the file that macro is defined, until corresponding undef or till end of the translation unit. So, your code would become, # define i 20 // from now on, all token i should become 20 void … Read more
-> is a shorthand for (*x).field, where x is a pointer to a variable of type struct account, and field is a field in the struct, such as account_number. If you have a pointer to a struct, then saying accountp->account_number; is much more concise than (*accountp).account_number;
char *test = (char*) malloc(12*sizeof(char)); +-+-+-+-+-+-+-+-+-+-+-+-+ test—>|x|x|x|x|x|x|x|x|x|x|x|x| (uninitialized memory, heap) +-+-+-+-+-+-+-+-+-+-+-+-+ test = “testingonly”; +-+-+-+-+-+-+-+-+-+-+-+-+ test + |x|x|x|x|x|x|x|x|x|x|x|x| | +-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+ +->|t|e|s|t|i|n|g|o|n|l|y|0| +-+-+-+-+-+-+-+-+-+-+-+-+ free(test); // error, because test is no longer pointing to allocated space. Instead of changing the pointer test, you need to copy the string “testingonly” into the allocated place using e.g. … Read more
Maybe it’s a little late (about 4 years), but here’s the best way i’ve found (for a c file): cut and paste the contents of the .c in the .h file, and for each function, put the cursor on it’s name and press Alt+Enter, and choose “Split function into declaration and definition”. this will keep … Read more