CODEWITHSUNDEEP
cgccinitializationwarnings
SealCuadrado
SealCuadrado

Reputation: 769

"Variable to be used not initialized" warning

This code I'm testing gives me a list of files that are in the current working directory. 

#include <stddef.h>
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>

int main (void)
{
    DIR *dp;
    struct dirent *ep;
    dp = opendir ("./");
    if (dp != NULL)
    {
        while (ep == readdir (dp))
        {
            puts (ep->d_name);
            (void) closedir (dp);
        }
    }
    else
        puts ("Couldn't open the directory.");
    return 0;
}

The code works, but the compilation with GCC gives me a warning telling me (I use GCC in Spanish) that can happen that the variable ep may be used without initializing in the function.

I've trying to give the variable ep a valor to avoid this warning (good practice of programming), but to do it results the program not doing what it's supposed to do.

Any idea what's going on, or what I'm doing wrong?

Upvotes: 1

Views: 335

Answers (3)

digital_revenant
digital_revenant

Reputation: 3324

You are equating an uninitialized variable ep to return value of a function in this line

while (ep == readdir(dp))

You want assignment

while ((ep = readdir(dp)))

If you want to read all the entries you may want to move closedir() outside the while loop

closedir(dp); //no need to cast

Upvotes: 4

Gangadhar
Gangadhar

Reputation: 10516

  puts (ep->d_name); //you are tried access uninitialized pointer

Actually you need to read directory using readdir , readdir returns struct dirent * Now store this return value into ep and need to check readdir is success or failed.

If an error occurs, NULL is returned and errno is set appropriately.

you need to check ep is NULL or not , but you are check ep == readdir(dp) 

  while (ep == readdir (dp)) ==> while (ep = readdir (dp))  
            ^^                             ^

For clear understanding you can write 

     while ( (ep == readdir (dp))  !=NULL)

Upvotes: 1

Eregrith
Eregrith

Reputation: 4366

You just need to write

while ((ep = readdir(dp)))

because writing == would not assign anything to ep.

The test for the while condition will happen on the result of the expression ep = readdir(dp), evaluated to ep final value.

Upvotes: 1

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