c - fclose causing exc_bad_access -

i can't figure out why fclose() in c program causing bad access. working fine , changed if condition print when strings not equal eachother , started causing problems. apart bad access error, not printing "newfile.txt"

    #include<stdio.h>     #include<stdlib.h>     #include <string.h>        int main()     {          file * cfile;         file *outputfile;          file *newfile;         cfile = fopen("input.in", "r");         if (cfile == null){         printf("bad input file");           }         newfile = fopen("newfile.txt", "w+");       if (newfile == null){         printf("bad newfile");      }         char tempstring[15];         char tempstring2[15];            //get each line in cfile        while (fscanf(cfile, "%15s", tempstring) != eof) {              outputfile = fopen("outputlotnum.txt", "r"); //open/(or reopen) outputfile  check lines           if (outputfile == null){         printf("bad outputfile");         }             //get each line in outputfile            while(fscanf(outputfile, "%15s", tempstring2) != eof){                   //if line cfile doesn't match line outputfile,                  //then go ahead , print line newfile.txt                if (strcmp(tempstring, tempstring2) != 0){                      fprintf(newfile,"%15s \n", tempstring2);                 }                   //else don't print , continue on next line             }             fclose(outputfile); //close outputfile after checking lines match         }          fclose(newfile); //throws bad access         fclose(cfile);           return 0;      } 

some reasons library functions seg faulting include passing bad parameters function or have memory scribbler. suspect in case have overflowed 1 or both temp string arrays on stack , have corrupted file handles. it's not safe operation fscanf/scanf buffer unless can guarantee string read fit buffer.

to confirm print out file handles after open, , again before close. should same. if not have accidentally overwritten them.