reading every file in directories (unix/posix) - c

Question

I'm stuck on unix system programming and am beginner about it. Assume that there is a directory which is X. There are a file(text1.txt) and another directory which is Y in X. Last, there are two files(text2.noExtension) and text3.noExtension) and another directory which is Z in Y. My goal is that read files and enter directories until there is no directory. Candidly, I really don't have any idea how to go on.
#include <dirent.h>
#include <errno.h>
#include <stdio.h>
int main(int argc, char *argv[]) {
struct dirent *direntp;
DIR *dirp;
if (argc != 2) {
fprintf(stderr, "Usage: %s directory_name\n", argv[0]);
return 1; }
if ((dirp = opendir(argv[1])) == NULL)
{
perror ("Failed to open directory");
return 1;
}
while ((direntp = readdir(dirp)) != NULL)
printf("%s\n", direntp->d_name);
while ((closedir(dirp) == -1) && (errno == EINTR)) ;
return 0;
}

Answer 1

If you want to list all directories and sub-directories, try something recursive. E.g.:
#include <dirent.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
void listOfDir(char * dirname, int level)
{
struct dirent *direntp;
DIR *dirp;
char *subdirname;
if ((dirp = opendir(dirname)) == NULL)
{
return;
}
while ((direntp = readdir(dirp)) != NULL)
{
if(strcmp(direntp->d_name, ".")==0 || strcmp(direntp->d_name, "..")==0)
continue; // skip current and parent directories
printf("%*c%s\n", level, '>', direntp->d_name);
if( direntp->d_type == 4)
{
// build child dir name and call listOfDir
subdirname = (char*)malloc(strlen(direntp->d_name) + strlen(dirname) + 2);
strcpy(subdirname, dirname);
strcat(subdirname, "/");
strcat(subdirname, direntp->d_name);
listOfDir(subdirname, level+1);
free(subdirname);
}
}
closedir(dirp);
}
int main(int argc, char *argv[]) {
struct dirent *direntp;
DIR *dirp;
if (argc != 2) {
fprintf(stderr, "Usage: %s directory_name\n", argv[0]);
return 1;
}
listOfDir(argv[1], 1);
return 0;
}
Expression like printf("%*c", level, '>') just make indents for elach level of nesting