c++ - Trying to understand the extern keyword -

i trying learn extern keyword.

i created file try2.cpp

#include <stdio.h> #include <conio.h>  extern int a;  int main() {      = 5;     printf("%d", a);     getch();     return 0; } 

and 1 try1.cpp

int a;  int main() {      = 10;     return 0; } 

but getting error in try2.c undefined. both files in bin folder of turboc.

what problem?

in try2.cpp, have:

extern int a; 

this tells compiler a defined externally - i.e. not within try2.cpp. so, must define externally, , need second .cpp file - lets make a.cpp file contains:

int a; 

you can compile each of try2.cpp , a.cpp:

tc -c try2.cpp tc -c a.cpp 

then need link them, specifying path cs.lib standard library file (search windows explorer if below doesn't work - updating \tc\lib\ path below):

tlink try2.obj + a.obj, program.exe, , \tc\lib\cs.lib 

that should create new program.exe run....

you should better compiler though....