CODEWITHSUNDEEP
clsdirent.h
user3501476
user3501476

Reputation: 1153

Implementing ls program in C using dirent.h

I am trying to implement the ls program using the dirent library. It appears that my DIR * mydir is of <unspecified type> when I debug with gdb, which says to me that it's as if I am not correctly including the dirent.h header, but I believe that I am correctly including all the required header files. 

#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/types.h> 
#include <sys/stat.h>

//Specifies whether or not to print hidden files
#define PRINT_HIDDEN 0

void readDirectory(char *dirString[]);

int main(int argc,char* argv[]) 
{
if(argc!=2)
{
printf("Usage: ./ls <directory>\n");
}

readDirectory(argv);    

return 0;
}

void readDirectory(char *dirString[])    
{
DIR *mydir; 
struct dirent *entry;
//Opening the directory and checking if valid
mydir = opendir(dirString[1]);  

if(mydir==NULL){
fprintf(stderr,"ls: cannot access %s: No such file or directory\n",
  dirString);
exit(EXIT_FAILURE);
}   
//Printing directories/files in specified directory
while((entry==readdir(mydir))!=NULL);
{
if(PRINT_HIDDEN)
{
  printf("%s ",entry->d_name);
}
else
{
  if(entry->d_name[0]!='.')
  {
    printf("%s ",entry->d_name);
  }
}
}
printf("\n");
//Closing the directory
closedir(mydir);
}

Upvotes: 0

Views: 3082

Answers (1)

chqrlie
chqrlie

Reputation: 145287

Well hidden in badly presented code lie two ugly bugs:

while((entry==readdir(mydir))!=NULL);
{
    ...
}

Use this instead:

while ((entry = readdir(mydir)) != NULL) {
    ...
}

entry is uninitialized, compiling with warnings enabled as by gcc -Wall would have spotted the problem. The extra ; at the end of the while condition is harder to spot, use a more consistent programming style to avoid such mistakes.

Upvotes: 6

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