c programming - can anyone explain to me how does the following code work recurs

Question

c programming - can anyone explain to me how does the following code work recursively? I highlighted the parts that I don't quit understand.

The code should be able to print out all of directory and its subdirectories recursively

#include <stdio.h>

#include<string.h>

void listdir(const char *name)

{

DIR *dir;

struct dirent *entry;

if (!(dir = opendir(name)))

return;

if (!(entry = readdir(dir)))

return;

do {

if (entry->d_type == DT_DIR) {

char path[1024];

int len = snprintf(path, sizeof(path)-1, "%s/%s", name, entry->d_name);

path[len] = 0;

if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)

continue;

printf("%s/%s ", name, entry->d_name);

listdir(path);

}

else

printf("%s/%s ",name, entry->d_name);

} while (entry = readdir(dir));

closedir(dir);

}

Explanation / Answer

#include <stdio.h>

#include<string.h>

void listdir(const char *name)

{

DIR *dir;

// Pointer for directory entry

struct dirent *entry;

// opendir returns NULL if couldn't open directory

if (!(dir = opendir(name)))

return;

if (!(entry = readdir(dir)))

return;

do {

if (entry->d_type == DT_DIR) {

char path[1024];

// checking lenagainst negative value

int len = snprintf(path, sizeof(path)-1, "%s/%s", name, entry->d_name);

   // path of length 0

path[len] = 0;

// returns FALSE if the current entry is the current directory (.) and the directory above this (..)

if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)

continue;

printf("%s/%s ", name, entry->d_name);

// returns a list containing the names of the entries in the directory given by path.

listdir(path);

}

else

printf("%s/%s ",name, entry->d_name);

} while (entry = readdir(dir));

closedir(dir);

}

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