c - Search function not working between files -

i have 2 files test2.c , comfunc.c

test2.c conatins

 #include "common.h"  #include <stdio.h>  #include <stdlib.h>   int main() {      printf("hello");      int n, i,po;     char *process=null;//stores host ip connected       char *ip = null,*port=null;//port connect     char *pch=null;      ip = malloc(50*sizeof(char));     pch = malloc(50 *sizeof(char));     port = malloc(50 * sizeof(char));     process = malloc(5 * sizeof(char));        //int n;         char str[650];      //int = 0, ret = 0;         struct data_struct *ptr = null;      ptr = openfile("server.cfg", o_rdonly);       ptr = search_in_list("clientip", null);      if ( ptr != null)     {         printf("\nclientip:%s\n",ptr->val);         ip =  ptr->val;     }     else     {         printf("can't find clientip connect\n");         exit(0);     }         ptr = search_in_list("port", null);      if ( ptr != null)     {         printf("\nport:%s\n",ptr->val);         port =  ptr->val;         //convert port no required format.         po = atoi(port);     }     else     {         printf("can't find port connect\n");         exit(0);      }           ptr = search_in_list("process", null);       if ( ptr != null)     {          printf("\nprocess:%s\n",ptr->val);         process =  ptr->val;     }     else     {         printf("can't find process create\n");         exit(0);      }   return 0; }; 

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and comfunc.c contains

  struct data_struct* search_in_list(char *val, struct data_struct **prev) {      char *dat=null;     char *dat2=null;     struct data_struct *ptr = head;     struct data_struct *tmp = null;     bool found = false;       while(ptr != null)     {      printf("values of val:=%s......ptr->val:=%s\n",val,ptr->val);            if (strcmp(val,ptr->val) == 0)         found = true;           if (found)         {             found = true;             break;         }         else         {             tmp = ptr;             ptr = ptr->next;         }     }      if(true == found)     {     ptr = ptr->next;         if(prev)             *prev = tmp;          return ptr;     }     else     {         return null;     } } 

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my problem search functions returns true values, if code of both adding_list , search_list both in same file.

but, if put code of adding list in comfunc.c , ptr = search_in_list("clientip", null) in test2.c, search never returns true values, returns null.

so question why such strange behavior. why below statement not comparing properly?

if (strcmp(val,ptr->val) == 0)     found = true;