Design a Program That Reads the Content of the Employee.dat File and Prints All the Data Within It

Write a C program to list all files in a directory. How to list all files in a directory recursively. How to use readdir() part to list all files in a directory recursively. Logic to list all files and sub-directories of a directory in C programming. How to use opendir(), readdir() and closedir() library functions.

Required knowledge

Basic Input Output, File handling, Recursion

In programming while file manipulation, several times we come beyond a problem to listing files in a directory. List files in a directory and recursively in its sub-directories. Notwithstanding, many C programmers don't know how to become list of all files and directories within a directory. In this post I volition explain how to list files and directories in a directory.

The readdir() function

          struct dirent *readdir(DIR *dirp);        

role is defined in dirent.h header file. It returns arrow to a structure dirent type representing directory entry at the current position in directory stream dirp. On every telephone call to readdir() method, information technology returns file/directory at electric current position in directory stream. readdir() returns NULL arrow if reached at the end of directory stream.

But wait, readdir(DIR *dirp) role accepts a parameter of DIR type. How to get reference to DIR type.

The opendir() function

          DIR *opendir(const char *dirname);        

is also defined in dirent.h header file. Similar to file streams, opendir() opens a directory stream corresponding to the file path pointed past dirname. Past default the opened directory stream points to first entry in the directory.

On success, the function returns a pointer to structure of DIR type. Otherwise NULL pointer. The returned value can be further used to perform operations on directory.

Similar to file stream, we open a directory stream, perform some activeness and finally close the stream. To shut a directory stream we use closedir() function.

The closedir() function

          int closedir(DIR *dirp);        

is as well present under same library file. It closes a directory pointed by dirp pointer.

On success the role returns 0, otherwise -1.

How to list all files and directories of a directory

Step by footstep descriptive logic to list all files and directories in a directory.

1. Input source path to list all files and sub-directories. Store it in some variable say path.
2. Open directory stream using opendir() and store its reference to *dir of DIR type.
3. Initialize another variable of pointer to structure dirent blazon, say struct dirent *dp.
4. Read next element from directory stream using dp = readdir(dir).
5. Print current directory stream particular proper noun, using dp->proper name.
6. Repeat step four-5 till dp != NULL.
7. Finally, shut the directory stream pointed by dir variable.

Program to listing all files and sub-directories in a directory

          /**  * C plan to listing all files and sub-directories in a directory.  */  #include <stdio.h> #include <sys/types.h> #include <dirent.h>   void listFiles(const char *path);  int master() {     // Directory path to list files     char path[100];      // Input path from user     printf("Enter path to listing files: ");     scanf("%s", path);      listFiles(path);      return 0; }   /**  * Lists all files and sub-directories at given path.  */ void listFiles(const char *path) {     struct dirent *dp;     DIR *dir = opendir(path);      // Unable to open directory stream     if (!dir)          return;       while ((dp = readdir(dir)) != Naught)     {         printf("%southward\n", dp->d_name);     }      // Close directory stream     closedir(dir); }        

Y'all tin easily convert above function to work for recursive directory list. Check below program if facing difficulties implementing it recursive way.

Plan to list all files and sub-directories of a directory recursively

          /**  * C program to list contents of a directory recursively.  */  #include <stdio.h> #include <cord.h>  void listFilesRecursively(char *path);   int chief() {     // Directory path to listing files     char path[100];      // Input path from user     printf("Enter path to list files: ");     scanf("%due south", path);      listFilesRecursively(path);      return 0; }   /**  * Lists all files and sub-directories recursively   * because path as base path.  */ void listFilesRecursively(char *basePath) {     char path[thousand];     struct dirent *dp;     DIR *dir = opendir(basePath);      // Unable to open up directory stream     if (!dir)         return;      while ((dp = readdir(dir)) != Nix)     {         if (strcmp(dp->d_name, ".") != 0 && strcmp(dp->d_name, "..") != 0)         {             printf("%south\n", dp->d_name);              // Construct new path from our base of operations path             strcpy(path, basePath);             strcat(path, "/");             strcat(path, dp->d_name);              listFilesRecursively(path);         }     }      closedir(dir); }}        

Enter path to listing files: . .git COMMIT_EDITMSG config description FETCH_HEAD Caput hooks pack ORIG_HEAD packed-refs refs heads primary remotes origin HEAD main tags .gitignore .vscode c_cpp_properties.json bin a.exe c-plan-to-notice-maximum-and-minimum-range-of-data-types-using-macro.c c-programming-ws.code-workspace data append.txt blanks.txt compare1.txt compare2.txt copy-file.txt empty-lines.txt even-numbers.txt file1.txt file2.txt file3.txt file4.txt merged-file.txt numbers.txt odd-numbers.txt prime-numbers.txt LICENSE README.physician src file append-information.c check-file-backdrop.c compare-file.c copy-file-contents.c re-create-file-using-function.c count-characters-words-lines-in-file.c count-occurrences-of-all-words-in-file.c create-and-write-contents-to-file.c delete-all-blank-lines.c delete-specific-line.c delete-give-and-take-from-file.c directory-exists.c file-exists.c file-programming-example-list.medico find-discussion-in-file.c list-files.c merge-file.c print-source-of-current-file.c read-from-file-using-fgetc.c read-from-file-using-fgets.c read-numbers-write-fifty-fifty-odd-prime-to-separate-file.c remove-empty-lines.c rename-file.c supplant-line-in-file.c supervene upon-give-and-take-in-file.c replace-word.c toggle-case-of-file-contents.c stdlib atof.c atoi.c atol.c atoll.c strtol.c strtoll.c strtoul.c strtoull.c

Let'due south raise the level. The in a higher place recursive method prints all files and sub-directories in aforementioned indentation. Its very difficult to know which files are in which directory. Then lets print all files and sub-directories in tree structure.

Program to print all files and sub-directories in tree structure

          /**  * C program to listing file and sub-directories of a directory   * recursively in tree structure.  */  #include <stdio.h> #include <cord.h> #include <sys/types.h> #include <dirent.h>   void tree(char *basePath, const int root);  int primary() {     // Directory path to list files     char path[100];      // Input path from user     printf("Enter path to list files: ");     scanf("%south", path);      tree(path, 0);      render 0; }   /**  * Tree, prints all files and sub-directories of a given   * directory in tree structure.  *   * @param basePath Base path to traverse directory  * @param root     Integer representing indention for electric current directory  */ void tree(char *basePath, const int root) {     int i;     char path[k];     struct dirent *dp;     DIR *dir = opendir(basePath);      if (!dir)         return;      while ((dp = readdir(dir)) != NULL)     {         if (strcmp(dp->d_name, ".") != 0 && strcmp(dp->d_name, "..") != 0)         {             for (i=0; i<root; i++)              {                 if (i%2 == 0 || i == 0)                     printf("%c", 179);                 else                     printf(" ");              }              printf("%c%c%due south\northward", 195, 196, dp->d_name);              strcpy(path, basePath);             strcat(path, "/");             strcat(path, dp->d_name);             tree(path, root + 2);         }     }      closedir(dir); }        

Enter path to list files: . ├─.git │ ├─COMMIT_EDITMSG │ ├─config │ ├─clarification │ ├─FETCH_HEAD │ ├─Caput │ ├─ORIG_HEAD │ ├─packed-refs │ ├─refs │ │ ├─heads │ │ │ ├─master │ │ ├─remotes │ │ │ ├─origin │ │ │ │ ├─HEAD │ │ │ │ ├─master │ │ ├─tags ├─.gitignore ├─.vscode │ ├─c_cpp_properties.json ├─bin │ ├─a.exe ├─c-programme-to-find-maximum-and-minimum-range-of-data-types-using-macro.c ├─c-programming-ws.code-workspace ├─data │ ├─suspend.txt │ ├─blanks.txt │ ├─compare1.txt │ ├─compare2.txt │ ├─copy-file.txt │ ├─empty-lines.txt │ ├─even-numbers.txt │ ├─file1.txt │ ├─file2.txt │ ├─file3.txt │ ├─file4.txt │ ├─merged-file.txt │ ├─numbers.txt │ ├─odd-numbers.txt │ ├─prime-numbers.txt ├─LICENSE ├─README.md ├─src │ ├─file │ │ ├─append-information.c │ │ ├─check-file-backdrop.c │ │ ├─compare-file.c │ │ ├─copy-file-contents.c │ │ ├─copy-file-using-function.c │ │ ├─count-characters-words-lines-in-file.c │ │ ├─count-occurrences-of-all-words-in-file.c │ │ ├─create-and-write-contents-to-file.c │ │ ├─delete-all-blank-lines.c │ │ ├─delete-specific-line.c │ │ ├─delete-give-and-take-from-file.c │ │ ├─directory-exists.c │ │ ├─file-exists.c │ │ ├─file-programming-instance-list.physician │ │ ├─find-word-in-file.c │ │ ├─list-files.c │ │ ├─merge-file.c │ │ ├─impress-source-of-current-file.c │ │ ├─read-from-file-using-fgetc.c │ │ ├─read-from-file-using-fgets.c │ │ ├─read-numbers-write-even-odd-prime number-to-dissever-file.c │ │ ├─remove-empty-lines.c │ │ ├─rename-file.c │ │ ├─supercede-line-in-file.c │ │ ├─replace-word-in-file.c │ │ ├─supervene upon-word.c │ │ ├─toggle-case-of-file-contents.c │ ├─stdlib │ │ ├─atof.c │ │ ├─atoi.c │ │ ├─atol.c │ │ ├─atoll.c │ │ ├─strtol.c │ │ ├─strtoll.c │ │ ├─strtoul.c │ │ ├─strtoull.c

Happy coding 😉

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Source: https://codeforwin.org/2018/03/c-program-to-list-all-files-in-a-directory-recursively.html

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