C get all files with certain extension

If you want to get the list of file name with the same extension in a folder with one system call, you can try to use scandir instead of using opendir and readdir. The only thing to remember is that you need to free the memory allocate by scandir.

 /* print files in current directory with specific file extension */ #include <string.h> #include <stdio.h> #include <stdlib.h> #include <dirent.h> /* when return 1, scandir will put this dirent to the list */ static int parse_ext(const struct dirent *dir) { if(!dir) return 0; if(dir->d_type == DT_REG) { /* only deal with regular file */ const char *ext = strrchr(dir->d_name,'.'); if((!ext) || (ext == dir->d_name)) return 0; else { if(strcmp(ext, ".ngl") == 0) return 1; } } return 0; } int main(void) { struct dirent **namelist; int n; n = scandir(".", &namelist, parse_ext, alphasort); if (n < 0) { perror("scandir"); return 1; } else { while (n--) { printf("%s\n", namelist[n]->d_name); free(namelist[n]); } free(namelist); } return 0; } 

C doesn't have standardised directory management, that's POSIX (or Windows if you're so inclined).
In POSIX, you can do something like:

1. Take the char * that contains the path to the directory
   
2. use opendir() on it, you get a DIR *
   
3. using readdir() on the DIR * repeatedly gives you the entries struct dirent* in the directory
   
4. the stuct dirent* contains the name of the file, including the extension (.ngl). It also contains info on whether the entry is a regular file or something else (a symlink, subdirectory, whatever)