libc

It seems that all my adult life I've been tormented by the VC++ linker complaining or balking because various libraries do not agree on which version of the Runtime library to use. I'm never in the mood to master that dismal subject. So I just try to mess with it until it works. The error messages are never useful. Neither is the Microsoft documentation on the subject - not to me at least. Sometimes it does not find functions - because the name-mangling is not what was expected? Sometimes it refuses to mix-and-match. Other times it just says, "LINK : warning LNK4098: defaultlib 'LIBCMTD'

What does f stand for in the name of C standard library functions? I have noticed that a lot of functions have an f in their name, and this does not really make sense to me. For example: fgets , fopen , printf , scanf , sqrtf and so on. Your question in general is too general but I can explain a few examples. f gets , f open , f close , … — The ”f“ stands for “file”. These functions accept or return a FILE * pointer as opposed to a file number as the POSIX functions do. print f , scan f , … — The ”f“ stands for “formatted”. These functions accept a format string. f print f , f scan f — This is

execvp is defined thus: int execvp(const char *file, char *const argv[]); Which precludes code such as this from being used: const char* argv[] = {"/bin/my", "command", "here", NULL}; execvp(argv[0], argv); Was this an accidental omission? Is it safe to const_cast around this? Or do some execvp implementations actually scribble on that memory? The POSIX spec says ( http://pubs.opengroup.org/onlinepubs/009604499/functions/exec.html ): The argv[] and envp[] arrays of pointers and the strings to which those arrays point shall not be modified by a call to one of the exec functions, except as a

Due to some obscure reasons which are not relevant for this question, I need to resort to use MAP_FIXED in order to obtain a page close to where the text section of libc lives in memory. Before reading mmap(2) (which I should had done in the first place), I was expecting to get an error if I called mmap with MAP_FIXED and a base address overlapping an already-mapped area. However that is not the case. For instance, here is part of /proc/maps for certain process 7ffff7299000-7ffff744c000 r-xp 00000000 08:05 654098 /lib/x86_64-linux-gnu/libc-2.15.so Which, after making the following mmap call ..

Where is ptrdiff_t defined in C? If non-trivial, how can I make this type visible from GCC on Linux? It's defined in stddef.h . That header defines the integral types size_t , ptrdiff_t , and wchar_t , the functional macro offsetof , and the constant macro NULL . It is defined by the POSIX standard: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stddef.h.html Where the type is exactly may be implemetation-specific, but interface is stddef.h Since @Good Person said this wasn't specific to Linux, in Microsoft Visual Studio, ptrdiff_t is defined in: C:\Program Files (x86)\Microsoft

I've give -lrt as the last linker flag to the compiler. But still getting this error. arif@khost:~/sak/sak.exosip$ gcc eXo_init.c -I/opt/osip2/include -I/opt/exosip/include -L/opt/osip2/lib -L/opt/exosip/lib -leXosip2 -losipparser2 -losip2 -lrt /opt/osip2/lib/libosip2.so: undefined reference to `clock_gettime' collect2: ld returned 1 exit status The man page says : NAME clock_getres, clock_gettime, clock_settime - clock and time functions SYNOPSIS #include <time.h> int clock_getres(clockid_t clk_id, struct timespec *res); int clock_gettime(clockid_t clk_id, struct timespec *tp); int clock