When i write a c program using a c library function say malloc , is the machine code for the malloc (which includes system calls or similar calls) present in the executable ?
or does every OS has to support the c library standard and the code for malloc is present here ?
I firmly believe that the first one is true ...
It depends on whether or not your program was linked statically or dynamically. This site has some information on the differences:
http://sunsite.uakom.sk/sunworldonli...l-02-perf.html
For instance, using this program:
I get the following executable sizes.Code:itsme@itsme:~/C$ cat malloc.c #include <stdio.h> #include <stdlib.h> int main(void) { void *p; if((p = malloc(100))) free(p); return 0; }
Dynamic linking:
Static linking:Code:itsme@itsme:~/C$ gcc -Wall malloc.c -o malloc itsme@itsme:~/C$ ls -l malloc -rwxr-xr-x 1 itsme users 10665 2006-05-11 08:09 malloc*
You can see that the statically linked executable is much, much larger.Code:itsme@itsme:~/C$ gcc -Wall -static malloc.c -o malloc itsme@itsme:~/C$ ls -l malloc -rwxr-xr-x 1 itsme users 467278 2006-05-11 08:09 malloc* itsme@itsme:~/C$
Last edited by itsme86; 05-11-2006 at 09:15 AM.
If you understand what you're doing, you're not learning anything.
Regardless, chances are you're going to have to make a syscall. In windows it has to pass through the memory manager, which is not present in your executable.
