26 string originalString = "123456789";
27 char[] buffer = originalString.ToCharArray();
28 Array.Reverse(buffer);
29 string reversedString = new String(buffer);
30
31 Console.WriteLine();
32 Console.WriteLine("original string: " + originalString);
33 Console.WriteLine("reversed string: " + reversedString);
To fill a string variable, sometimes, they use next way: const string breakLine = "----------";
Seems, next way (usage one of string’s constructor) will be better:
string line = new string('-', 10);
Console.WriteLine("new string('-', 10) >" + line);
Console Output:
To sort array (or list) of a objects, we need compare 2 objects and define number:
0 - when 2 objects are same;
+1 - when a 1st object more than 2nd;
-1 - when a 1st object less than 2nd.
Samples:
Sign of number:
int x;
Console.WriteLine(Environment.NewLine + "int x");
Console.WriteLine("Math.Sign({0}) = {1}", x = 10, Math.Sign(x));
Console.WriteLine("Math.Sign({0}) = {1}", x = -10, Math.Sign(x));
Console.WriteLine("Math.Sign({0}) = {1}", x = 0, Math.Sign(x));
Compare 2 strings:
string s1;
string s2;
bool ignoreCase;
Console.WriteLine();
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "a", s2 = "b", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "b", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "a", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "aa", s2 = "b", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "bb", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "A", s2 = "b", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "B", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\", {2}) = {3}", s1 = "a", s2 = "A", ignoreCase = false, String.Compare(s1, s2, ignoreCase));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\", {2}) = {3}", s1 = "a", s2 = "A", ignoreCase = true, String.Compare(s1, s2, ignoreCase));
Compare 2 DateTime objects:
DateTime d1;
DateTime d2;
Console.WriteLine();
Console.WriteLine("DateTime.Compare({0}, {1}) = {2}", d1 = new DateTime(2007, 10, 1), d2 = new DateTime(2007, 10, 1), DateTime.Compare(d1, d2));
Console.WriteLine("DateTime.Compare({0}, {1}) = {2}", d1 = new DateTime(2006, 10, 1), d2 = new DateTime(2007, 10, 1), DateTime.Compare(d1, d2));
Console.WriteLine("DateTime.Compare({0}, {1}) = {2}", d1 = new DateTime(2008, 10, 1), d2 = new DateTime(2007, 10, 1), DateTime.Compare(d1, d2));
Console output:
Reference:
When we use Generic class List(T), we can easy to sort it with help of method Sort and delegate Comparison.
Sample.
Definition of class Data:
internal class Data
{
internal int id;
internal string name;
internal Data(int id, string name)
{
this.id = id;
this.name = name;
}
}
Initialization of List<Data>:
List<Data> dataList = new List<Data>();
dataList.Add(new Data(4, "London"));
dataList.Add(new Data(2, "Rome"));
dataList.Add(new Data(3, "New York"));
dataList.Add(new Data(5, "Paris"));
dataList.Add(new Data(1, "Jerusalem"));
DataServices.PrintList("by original order:", dataList);
Sorting dataList by field id:
dataList.Sort(delegate(Data data1, Data data2) { return data1.id - data2.id; });
DataServices.PrintList("by id:", dataList);
Sorting dataList by field name:
dataList.Sort(delegate(Data data1, Data data2) { return String.Compare(data1.name, data2.name); });
DataServices.PrintList("by name:", dataList);
Console output:
Reference:
Comparison(T) Generic Delegate
New build of ReferencesManager (v1.0.2) is released.
The build include new command line switch:
-path=<customer path>
which allows to define additional folders to search referenced assemblies. For example:
ReferencesManager.exe Main.dll -path=D:\0;D:\1
Downloading ReferencesManager 1.0.2
Sources can be downloaded from "C# tips samples" project.
References:
When we need to align output of strings we can use method String.PadLeft() or String.PadRight():
Sample:
string[] initialData = new string[]
{"one", "two",
"three", "four", "five"};
Console.WriteLine("PadLeft sample");
foreach (string item in initialData)
{
string processedItem = item.PadLeft(10, '.');
Console.WriteLine("'{0}'", processedItem);
}
Console.WriteLine("PadRight sample");
foreach (string item in initialData)
{
string processedItem = item.PadRight(10, '.');
Console.WriteLine("'{0}'", processedItem);
}
Console output:
Reference:
When we should create a string, which consists of array of strings with a separator usually we use a iterator (for, foreach).
For example,
string[] stringData = new string[] {"one", "two", "three"};
string outputContent1 = "";
foreach (string item in stringData)
{
outputContent1 += item + ";";
}
outputContent1 = outputContent1.Remove(outputContent1.Length - 1);
Debug.Print("output #1: {0}", outputContent1);
Now, we can use csharp (c#) method String.Join:
string outputContent2 = String.Join(";", stringData);
Debug.Print("output #2: {0}", outputContent2);
Output window:
Reference:
To remove leading and trailing characters from string in csharp (c#) we can use methods String.Trim(), String.TrimEnd() or String.TrimStart().
Samples:
originalLine = " message with space, ";
actualLine = originalLine.Trim();
DisplayMessage(originalLine, actualLine);
originalLine = " message with space, ";
actualLine = originalLine.TrimEnd();
DisplayMessage(originalLine, actualLine);
originalLine = " message with space, ";
actualLine = originalLine.TrimStart();
DisplayMessage(originalLine, actualLine);
originalLine = " message with space, ";
actualLine = originalLine.Trim(new char[] { ' ', ',' });
DisplayMessage(originalLine, actualLine);
Sometimes interesting to see implementation of C# methods.
So, let's see method String.Trim(Char[]):
// Removes a string of characters from the ends of this string.
public String Trim(params char[] trimChars) {
if (null==trimChars || trimChars.Length == 0) {
trimChars=WhitespaceChars;
}
return TrimHelper(trimChars,TrimBoth);
}
and basic method TrimHelper():
private String TrimHelper(char[] trimChars, int trimType) {
//end will point to the first non-trimmed character on the right
//start will point to the first non-trimmed character on the Left
int end = this.Length-1;
int start=0;
//Trim specified characters.
if (trimType !=TrimTail) {
for (start=0; start < this.Length; start++) {
int i = 0;
char ch = this[start];
for( i = 0; i < trimChars.Length; i++) {
if( trimChars[i] == ch) break;
}
if( i == trimChars.Length) { // the character is not white space
break;
}
}
}
if (trimType !=TrimHead) {
for (end= Length -1; end >= start; end--) {
int i = 0;
char ch = this[end];
for(i = 0; i < trimChars.Length; i++) {
if( trimChars[i] == ch) break;
}
if( i == trimChars.Length) { // the character is not white space
break;
}
}
}
//Create a new STRINGREF and initialize it from the range determined above.
int len = end -start + 1;
if (len == this.Length) {
// Don't allocate a new string is the trimmed string has not changed.
return this;
}
else {
if( len == 0) {
return String.Empty;
}
return InternalSubString(start, len, false);
}
}
References:
When we should divide a string to array of strings by a specific delimiters, we can use method String.Splt().
Samples:
string line = "name,id=1234,,description,user=Jon";
string[] lineItems = line.Split(new char[] { ',' });
DisplayOutput(line, lineItems);
lineItems = line.Split(new char[] { ',', '=' });
DisplayOutput(line, lineItems);
lineItems = line.Split(new char[] { ',', '=' }, 2);
DisplayOutput(line, lineItems);
lineItems = line.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
DisplayOutput(line, lineItems);
lineItems = line.Split(new string[] { ",", "id=", "user="}, StringSplitOptions.RemoveEmptyEntries);
DisplayOutput(line, lineItems);
References:
Sometimes, when a complex project (many source solutions, dlls, references) is built and run, then we receive a problem with references (here we don't speak about signed assemblies). For example, all dlls has a reference to basic .dll, but a specific .dll has a reference to obsolete version of the basic .dll.
Sample:
MainUtils has a reference to Utils1 (v2.0.0.0) and Utils2 (v2.0.0.0), but Utils2 (v2.0.0.0) has a reference to obsolete version of Utils1 (v1.0.0.0). See folders TestData4References in solution csharp-samples.
When a MainUtils will be run, then a error can be shown.
Utility ReferencesManager.exe helps to show all references and output list of all assemblies full names. This information helps to see same assemblies with different versions.
To start the utility it is necessary to type name of initial executable (or .dll) file:
ReferencesManager.exe MainUtils.exe > MainUtils.log
Content of MainUtils.log:
Received log allows to find Utils1 with different versions 1.0.0.0 and 2.0.0.0 and Utils2, which references to Utils1 version 1.0.0.0.
Limitations of version 1.0.1:
Downloading ReferencesManager.exe.
References:
To convert one simple type (for example int), to another simple type (for example float or string) it is suggested to use .NET class BitConverter.
C# code sample:
static void Main()
{
int intData = 0x01020304;
byte[] bytesData = BitConverter. GetBytes(intData);
float floatData = BitConverter.ToSingle(bytesData, 0);
string stringData = BitConverter.ToString(bytesData);
}
Result values (from VS Locals Window):
Reference:
To convert byte array to string it is suggested to use class Encoding
class ConvertUtils:
public class ConvertUtils
{
public static string ConvertBytesToString(byte[] data)
{
return Encoding.GetEncoding(1251).GetString(data);
}
public static byte[] ConvertStringToBytes(string data)
{
return Encoding.GetEncoding(1251).GetBytes(data);
}
}
Example:
It is a very important to test converting with help of 0xFD..0xFF (253 - 255) values, because a some code pages cannot convert these values correct.
byte[] inputData = new byte[] {0, 1, 2, 3, 0xFD, 0xFE, 0xFF};
string convertedData = ConvertUtils.ConvertBytesToString(inputData);
byte[] outputData = ConvertUtils.ConvertStringToBytes(convertedData);
Results:
Reference
If it is necessary to check string variable on null and "" (empty), then
function String.IsNullOrEmpty can be used:
c0de with operator 'if'
string getName(string name)
{
if (name == null || name == "")
return "default";
else
return name;
}string getName_with_function_IsNullOrEmpty(string name)
{
if (String.IsNullOrEmpty(name))
return "default";
else
return name;
}
Sample can be download:
http://code.google.com/p/csharp-tips/source/browse/trunk/string_functions/Program.cs
Additional Links:
String..::.IsNullOrEmpty Method