Introduction to C# File.Exists
In C#, File.Exists() method comes under System.IO namespace. It is used to check whether a file exists at the specified location or not. The following are some important points regarding File.Exists() method in C#:
- This method takes a string (path of the file) as input.
- It returns a Boolean value; returns true if the user has required permission to read the file and the file exists at the specified location else returns false.
- It also returns false if the path is null or if it is not valid or if its length is zero.
Syntax:
The syntax for File.Exists() method in C# is as follows:
if(File.Exists(file_path))
{
//user code
}In the above syntax, we have used File.Exists() method with an ‘if’ statement. Here, File is a class that contains the Exists() method. The File.Exists() method takes ‘file_path’ which is the path of the file as input to check if the file exists or not.
If the file exists then the corresponding user code will be executed.
How File.Exists() Method Works in C#?
To work with File.Exists() method, we first need to import System.IO namespace in our code. This method takes a string as an input which is the path of the file to be checked for existence. This method returns true if the file exists at the specified path and if the user has permission to read the file. If the file exists but the user does not have required permission to read the file then an exception will not be thrown but the method will return false. Apart from this, the method returns false if the input string (path of the file) is null or if its length is zero. The user should check that the path of the file is valid such as it is not empty, it does not only contain white spaces, it does not contain any invalid characters, the path of the file or file name is not too long, etc. If the path of the file is not valid then the method will return false.
We can check for the validity of the path by calling Path.GetInvalidPathChars() method which returns an array of characters that are not allowed in the pathname. Along with this, we can also create a regex (regular expression) to check for the validity of the path. While a user calls File.Exists() method on a file it is possible that at the same time another operation can be performed on the same file such as Delete operation. Thus, a user needs to be aware of this possibility. To File.Exists() method, the user is allowed to pass absolute or relative path information as input. The path specified as a relative path will be interpreted as relative to the current working directory. File.Exists() method works only for a file. If a user passes the path of the directory to the method then it will return false. The method removes trailing spaces if any from the path of the file before checking for the existence of the file.
Examples of File.Exists in C#
Example to check if the file exists in the current directory or not. If it exists the code will open the file to read its content else it will show a message that file does not exist in this directory.
Example #1
Code:
using System;
using System.IO;
namespace ConsoleApp4
{
public class Program
{
public static void Main()
{
string filePath = "Text.txt";
string fileContent = string.Empty;
try
{
//checking if file exists in the current directory
if (File.Exists(filePath))
{
//opening text file and reading the whole content
using (TextReader tr = File.OpenText(filePath))
{
fileContent = tr.ReadToEnd();
Console.WriteLine(fileContent);
}
}
else
{
Console.WriteLine(filePath + " file does not exist in the current "+
"directory.");
}
}
catch(Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.ReadLine();
}
}
}Output:
Example #2
Example to check if a file exists at the specified directory by writing the file path in two different ways as shown below:
- The first way is to prefix the ‘@’ symbol to the file path. This requires a single ‘\’ backslash in the file path.
- The other way is to provide two backslashes ‘\\’ in the file path.
Code:
using System;
using System.IO;
namespace ConsoleApp4
{
public class Program
{
public static void Main()
{
string filePath1 = @"D:\Content\FileExists.txt";
string filePath2 = "D:\\Content\\FileExists.txt";
string fileContent = string.Empty;
try
{
//checking if file exists in the specified directory
if (File.Exists(filePath1))
{
Console.WriteLine("Reading file content using first way of " +
"writing file path");
//opening text file and reading the whole content
using (TextReader tr = File.OpenText(filePath1))
{
fileContent = tr.ReadToEnd();
Console.WriteLine(fileContent);
}
}
else
{
Console.WriteLine(filePath1 + " file does not exist in " +
"the specified directory.");
}
if (File.Exists(filePath2))
{
Console.WriteLine("\nReading file content using second way of " +
"writing file path");
fileContent = string.Empty;
//opening text file and reading the whole content
using (TextReader tr = File.OpenText(filePath2))
{
fileContent = tr.ReadToEnd();
Console.WriteLine(fileContent);
}
}
else
{
Console.WriteLine(filePath2 + " file does not exist in " +
"the specified directory.");
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.ReadLine();
}
}
}Output:
Example #3
Example showing File.Exists() method working with the ‘null’ file path.
Code:
using System;
using System.IO;
namespace ConsoleApp4
{
public class Program
{
public static void Main()
{
//taking file path as 'null'
string filePath = null;
string fileContent = string.Empty;
try
{
//checking if file exists
if (File.Exists(filePath))
{
//opening text file and reading the whole content
using (TextReader tr = File.OpenText(filePath))
{
fileContent = tr.ReadToEnd();
Console.WriteLine(fileContent);
}
}
else
{
Console.WriteLine(filePath + " file does not exist.");
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.ReadLine();
}
}
}
Output:
In the above example, File.Exists() method returned false because the file path is ‘null’.
Conclusion
- Exists() method in C# is used in file handling. It is used to check if a file exists or not.
- This method takes the path of the file as input.
- The method returns ‘true’ if the file exists at the specified path else it returns ‘false’.
Recommended Articles
This is a guide to C# File Exists. Here we discuss the introduction and how file.exists() method works in C# along with different examples and its code implementation. You may also look at the following articles to learn more –
