- Posted by Shay Friedman on January 16, 2010
During our everyday programming tasks we run into several repetitive code blocks that after the 20th time you implement them become really annoying. The worst case is to re-implement these code blocks every time, and the better case is to create a central class library with helper classes and methods. However, a large amount of these tasks can be achieved easily with built-in .NET methods.
In this post I will go through several repetitive code blocks and show you how to implement them using built-in .NET method. If you want to add your suggestions, comment! I’ll add your suggestions to the post periodically.
Disclaimer: I’m sure some of the code blocks I use in the NOT Recommended sections can be written much better. These code blocks are here just for demonstration purposes.
Code Block #1 – Check string for nullity or emptiness
NOT Recommended
str = "something"
if (str == null || str == String.Empty)
{
// Oh no! the string isn't valid!
}Recommended
str = "something"
if (String.IsNullOrEmpty(str))
{
// Oh no! the string isn't valid!
}Code Block #2 – Check string for nullity or emptiness (spaces only string is invalid too)
NOT Recommended
str = "something"
if (str == null || str.Trim() == String.Empty)
{
// Oh no! the string isn't valid!
}Recommended (C# 4.0 Only)
str = "something"
if (String.IsNullOrWhiteSpace(str))
{
// Oh no! the string isn't valid!
}Code Block #3 – Copy an Array
NOT Recommended
string[] source = new string[] { "a", "b", "c" };
string[] dest = new string[3];
for (int i=0; i < source.Length; i++)
{
dest[i] = source[i];
}Recommended
string[] source = new string[] { "a", "b", "c" };
string[] dest = new string[3];
Array.Copy(surce, dest, source.Length);Code Block #4 – Check if a char is a digit
NOT Recommended
char c = '1';
if (c == '1' || c == '2' || c == '3' ||
c == '4' || c == '5' || c == '6' ||
c == '7' || c == '8' || c == '9' ||
c == '0')
{
// It's a digit!
}Recommended
char c = '1';
if (Char.IsDigit(c))
{
// It's a digit!
}Code Block #5 – Combine Paths
NOT Recommended
string folder = @"C:\MyDir";
string file = "MyFile.docx";
// Combine to make a path
string path = folder + @"\" + file;
Recommended
string folder = @"C:\MyDir";
string file = "MyFile.docx";
// Combine
string path = System.IO.Path.Combine(folder, file);
Code Block #6 – Get file extension out of a file path
NOT Recommended
string path = @"C:\MyDir\MyFile.docx";
string extension = path.Substring(path.LastIndexOf("."));Recommended
string path = @"C:\MyDir\MyFile.docx";
string extension = System.IO.Path.GetExtension(path);
Code Block #7 – Get MyDocuments Path
NOT Recommended
// Probably some nasty stuff here
Recommended
Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
Code Block #8 – Check if object is of a specific type
NOT Recommended
object obj = "str";
if (obj.GetType() == typeof(String))
{
// It's a string!
}Recommended
object obj = "str";
if (obj is String)
{
// It's a string!
}As Adrian Aisemberg has pointed out, these samples are not entirely the same. The is keyword will return true also if obj is of a derivative type of String (in this sample).
Code Block #9 – Set default enum value
NOT Recommended
public class MyClass
{
private enum Sample
{
A,
B,
C
}
static Sample s = Sample.B; // Set default value explicitly
public static void Run()
{
Console.WriteLine(s); // Prints B
}
}Recommended
public class MyClass
{
private enum Sample
{
A,
B = 0, // Make B the default value
C
}
static Sample s; // Default value will be used
public static void Run()
{
Console.WriteLine(s); // Prints B
}
}Code Block #10 – Check if a string starts with another string
NOT Recommended
string str = "Hello World";
if (str.Substring(0, 5) == "Hello")
{
// String starts with Hello!
}Recommended
string str = "Hello World";
if (str.StartsWith("Hello"))
{
// String starts with Hello!
}Code Block #11 – Convert list of items of one type to a list of items of a different type
NOT Recommended
List<int> list = new List<int>(new[] { 1, 2, 3, 4, 5 });
List<string> convertedList = new List<string>();
foreach (int item in list)
{
convertedList.Add(item.ToString());
}Recommended
List<int> list = new List<int>(new[] { 1, 2, 3, 4, 5 });
List<string> convertedList = list.ConvertAll<string>(Convert.ToString);Code Block #12 – Check if a string contains a number and get the number
NOT Recommended
string str = "4";
int num = 0;
bool success = false;
try
{
num = Convert.ToInt32(str);
success = true;
}
catch
{
success = false;
}
if (success)
{
// Do something with the number
}Recommended
string str = "4";
int num = 0;
if (Int32.TryParse(str, out num))
{
// Do something with the number
}Code Block #13 – Writing a string to a file (courtesy of Yaron Naveh)
NOT Recommended
const string str = "put me in a file";
const string file = @"c:\logs\file.txt";
var fs = new FileStream(file, FileMode.Create);
var sw = new StreamWriter(fs);
sw.Write(str);
sw.Close();
fs.Close();
Recommended
const string str = "put me in a file";
const string file = @"c:\logs\file.txt";
File.WriteAllText(file, str);
Code Block #14 – Pick value if not null and a different on if it is (courtesy of Abhishek)
NOT Recommended
string input = "sdfds";
string result = null;
if (input == null)
{
result = "Input is null!";
}
else
{
result = input;
}Recommended
string input = "sdfds";
string result = input ?? "Input is null!";
This is it for now. If you have more, comment and I’ll add your suggestions to the list (with credits).
All the best,
Shay.