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); // what exactly does snprintf do?

path[len] = 0; // what does this statement mean? why set it to 0?

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

continue;

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

listdir(path); //How does it been called recursively

}

else

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

} while (entry = readdir(dir));

closedir(dir);

}

Explanation / Answer

Solution:

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

path - The output “name” and “entry->d_name” is redirected to the string path.(path is the pointer to path[0])

sizeof(path)-1 - Is the maximum number of bytes(characters) that will be written to the string path.

%s%s- String format

len - snprintf returns the size of the format string after substitution.

path[len] = 0; - adds 0 at the end of the path, to denote the end

Note: snprintf() automatically appends a null character to the character sequence resulting from format substitution.

listdir(path); //How does it been called recursively

listdir(path); - is a calling statement to itself with the argument path.

Note: listdir(path); is within the function definition of void listdir(const char *name), thus it calls itself(recursion).

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