Explain the below C Program syntax and what its doing? I\'m a Java guy, having d

Question

Explain the below C Program syntax and what its doing? I'm a Java guy, having difficulty understanding. Output of the code is also shown below. Line by Line brief explanation would be helpful. ***DO NOT EXPLAIN THE MAIN METHOD and INCLUDES*** (Those are provided for clarity only.).

/* printdir1.c
*/

#include
#include
#include
#include
#include
#include

void printdir(char *dir, int depth)
{
DIR *dp;
struct dirent *entry;
struct stat statbuf;

if((dp = opendir(dir)) == NULL) {
fprintf(stderr,"cannot open directory: %s ", dir);
return;
}

chdir(dir);

while((entry = readdir(dp)) != NULL) {
lstat(entry->d_name,&statbuf);

if(S_ISDIR(statbuf.st_mode)) {
/* Found a directory, but ignore . and .. */
if(strcmp(".",entry->d_name) == 0 ||
strcmp("..",entry->d_name) == 0) {
continue;
   }

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

/* Recurse at a new indent level */
printdir(entry->d_name,depth+4);
}
else {
printf("%*s%s ",depth,"",entry->d_name);
}
}
chdir("..");
closedir(dp);
}

/* Now we move onto the main function. */

int main()
{
printf("Directory scan of /home: ");
printdir("./",0); // print current directory entries
printf("done. ");

exit(0);
}

OUTPUT:

Directory scan of /home:

.cproject

.project

Debug/

Assignment_1

makefile

objects.mk

printdir1.d

printdir1.o

sources.mk

subdir.mk

printdir1.c

done.

Explanation / Answer

//I have added more comments for u to understand it better

//Preprocessing directives

#include
#include
#include
#include
#include
#include

//Function defination in c.This function takes 2 paramters.One is a pointer variable and the other one is a normal //variable

void printdir(char *dir, int depth)
{

//pointer variable declaration in c.A pointer variable is the variable which keeps the address of other or //normal variable.Here DIR is a directory pointer

DIR *dp;
struct dirent *entry;
struct stat statbuf;

//opening a directory.i.e If dp pointer contains null value,then we cannot open a directory.So appropriate //error message is printed.In c fprintf and fscanf //commands are used when we deal with writing and //reading from files.If dp variable is one means,we can open a directory

if((dp = opendir(dir)) == NULL) {
fprintf(stderr,"cannot open directory: %s ", dir);
return;
}

chdir(dir);

while((entry = readdir(dp)) != NULL) {
lstat(entry->d_name,&statbuf);

if(S_ISDIR(statbuf.st_mode)) {
/* Found a directory, but ignore . and .. */
if(strcmp(".",entry->d_name) == 0 ||
strcmp("..",entry->d_name) == 0) {
continue;
   }

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

/* Recurse at a new indent level */
printdir(entry->d_name,depth+4);
}
else {
printf("%*s%s ",depth,"",entry->d_name);
}
}
chdir("..");

//command to close a directory.This we do by closing the pointer variable,which holds its value.

closedir(dp);
}

/* Now we move onto the main function. */

int main()
{
printf("Directory scan of /home: ");
printdir("./",0); // print current directory entries
printf("done. ");

exit(0);
}

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