Creates all directories and subdirectories unless they already exist and creates or overwrites a file in the specified path. License: MIT

CreateFileAndDirectory.cs

using System;
using System.IO;

/// <summary>
/// Creates all directories and subdirectories unless they already exist and creates or overwrites a file in the specified path.
/// </summary>
/// <param name="path">The full path of the file.</param>
public static FileStream CreateFileAndDirectory(string path)
{
  if (path == null) { throw new ArgumentNullException(nameof(path)); }
  if (string.IsNullOrWhiteSpace(path)) { throw new ArgumentException("path cannot be empty."); }

  string fileName = Path.GetFileName(path);
  string directory = Path.GetDirectoryName(path);
  return CreateFileAndDirectory(fileName, directory);
}

/// <summary>
/// Creates all directories and subdirectories unless they already exist and creates or overwrites a file in the same path.
/// </summary>
/// <param name="fileName">The name of the file.</param>
/// <param name="directory">The directory to create.</param>
public static FileStream CreateFileAndDirectory(string fileName, string directory)
{
  if (fileName == null) { throw new ArgumentNullException(nameof(fileName)); }
  if (string.IsNullOrWhiteSpace(fileName)) { throw new ArgumentException("fileName cannot be empty."); }
  if (directory == null) { throw new ArgumentNullException(nameof(directory)); }
  if (string.IsNullOrWhiteSpace(directory)) { throw new ArgumentException("directory cannot be empty."); }

  Directory.CreateDirectory(directory);

  string path = directory + (directory.EndsWith("\\") ? string.Empty : "\\") + fileName;
  return File.Create(path);
}