c - Use the value of global variable in any other function as its value changes inside another function -

say using global variable hold value of signal (in schematics circuit board sense) in 1 function

void randomfunction() {     for(t=lnnew,s=node->name;*s;)     {     if()          //some code      else       *t=*s;     t++;     s++;     } printf("%s \n",lnnew);   //so here lnnew holding new values of signal , when print this, every time new value of signal printed , have declared global } 

now how can use global variable inside other function writelnnewvalue() when ever value of lnnew changes in randomfunction(), changes , printed in writelnnewvalue () function?

i had asked similar type of question in this link , if seems exact copy mark duplicate.

you need declare variable in header (.h file) included in compilation units use it:

extern volatile int lnnew; 

have 1 compilation unit (.c file) define it

volatile int lnnew; 

then usable everywhere include header. volatile here indicates compiler that variable subject unpredictable changes , not cached.