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layout: post title: "List all files in a directory using C language in UNIX environment" date: 2026-03-24 00:00:00 +0800 categories: [CPlus] tags: [cpp, cmake]

Demonstrate listing all files in a directory using C language in a UNIX environment

Test Environment

Tested successfully on Ubuntu 24.04. It should work in other UNIX-like environments as well. Windows is theoretically not supported.

Source Code Snippet

#include <stdio.h>
#include <dirent.h>

int main(int argc, char *argv[]) {
  printf("hello %s\n", "world");

  DIR *dp;
  struct dirent *dirp;

  if (argc != 2) {
    return 1;
  }

  if ((dp = opendir(argv[1])) == NULL) {
    fprintf(stderr, "can't open %s", argv[1]);
    return 2;
  }

  while((dirp = readdir(dp)) != NULL) {
    printf("%s\n", dirp->d_name);
  }

  closedir(dp);
  return 0;
}

Complete source code address: pnnh/apue-listfile

Source Code Explanation

Calling opendir returns a DIR*, which is an opaque pointer to a specific directory. Subsequent directory operation functions require this pointer to be passed.

Calling readdir returns a dirent*, which points to an entry in the directory, possibly a file or folder, containing the file name.

After directory operations are complete, closedir must be called to close the directory to prevent resource leaks.

Compilation

Enter the source code directory and execute the following commands:

mkdir cmake-build && cd cmake-build
cmake ..
make

An executable file named ApueListfile will be generated in the build directory.

If a compilation error occurs, please repeat the above compilation steps based on the error message.

Execution

Run the program using the command ./ApueListfile <directory>

Here, <directory> must be an absolute directory path. For example, the following commands will execute successfully:

./ApueListfile /tmp
./ApueListfile /home
./ApueListfile /var