c - fseek() and ftell() fail in a loop -

i need loop trough directory, data , read each file, meets conditions, in string , it. reason fails after fseek call (the output name of first file in directory).

any idea doing wrong?

#include <stdio.h> #include <stdlib.h> #include <dirent.h> #include <string.h>  void doalgorithm(char *input) {     printf("%s\n", input); }  int main(int argc, char** argv) {     struct dirent *dir;     dir *d = opendir("data");     file *file;     while ((dir = readdir(d)) != null) {         if (strlen(dir->d_name) > 6 && dir->d_name[6] == 'i') {             printf("filename: %s\n", dir->d_name);             file = fopen(dir->d_name, "r");             fseek(file, 0, seek_end);             long length = ftell(file);             fseek(file, 0, seek_set);             printf(", filesize: %ld\n", length);              char *buffer = malloc(length + 1);             fread(buffer, 1, length, file);             buffer[length] = '\0';              fclose(file);             doalgorithm(buffer);         }     }     closedir(d);     return (exit_success); } 

your problem file = fopen(dir->d_name, "r"); doesn't know file in directory. need give full path. can this;

    struct dirent *dir;    // put directory path here. on windows \ instead of /     char *path = "/users/adnis/clion/stackoverflow/testdir";     char *slash = "";     dir *d = opendir(path);     file *file;         while ((dir = readdir(d)) != null) {        if (strlen(dir->d_name) > 6 && dir->d_name[6] == 'i') {                 printf("filename: %s\n", dir->d_name);                 int length = strlen(path);         /*check if path contains '/' @            end before joining filename directory*/                  if(path[strlen(path)-1] != '/'){ //on windows '\'                    slash = "/";                 }                  length += strlen(dir->d_name)+2;      // allocate memory new path      // , make sure have enough memory.                 char *newpath = malloc(length);                  assert(newpath != null);                  snprintf(newpath,length,"%s%s%s",path,slash,dir->d_name);                  file = fopen(newpath, "r");                 if(file == null){                     fprintf(stderr, "fopen: %s\n", strerror(errno));                     break;                 }                 fseek(file, 0, seek_end);                 long len = ftell(file);                 fseek(file, seek_set, 0);                  char *buffer = malloc(len + 1);                 fread(buffer, 1, len, file);                 buffer[strlen(buffer)] = '\0';                  printf("%s \n",buffer);                 fclose(file);             }         }         closedir(d);         return (exit_success); 

i suggest when reading directory have try , avoid reading "." , ".." since current directory , previous directory. help. in while loop

if(strcmp(dir->d_name,".") == 0 || strcmp(dir->d_name,"..") == 0)             continue;