readdir() is a C standard library function, included in dirent.h, used to read filesystem directory streams.
readdir() is used in conjunction with opendir() and closedir()
#include <stdio.h>
#include <dirent.h>
int main() {
DIR *dir;
struct dirent *entry;
dir = opendir(".");
if (dir == NULL)
return 1;
while ((entry = readdir(dir)) != NULL)
printf("%s\n", entry->d_name);
closedir(dir);
return 0;
}