CSharp Common String Operations Part-I

Common String Operation Part I

We have compiled some common string operations in this article that we encounter while working with the string class. We covered 15 common string operations in Part I. We're going to continue this article in the next article and cover 15 more.

First we declared two string variables strOriginal and strModified. All the examples are based on these two pre-declared string variables.

C#

string strOriginal = "These are string Examples";
string strModified = string.Empty;

VB.Net

Dim strOriginal As String = "These are string Examples"
Dim strModified As String = string.Empty

 

 

Iterate a String

We can use the "for loop" or "foreach loop" to iterate through a string. The "for loop" gives us more flexibility over the iteration.

For Example:

For Loop in C#

for (int i = 0; i < strOriginal.Length; i++)
    {
        MessageBox.Show(strOriginal[i].ToString());
    }

For Each Loop in C#

foreach (char c in strOriginal)
    {
        MessageBox.Show(c.ToString());
    }

For Loop in VB.Net

For i As Integer = 0 To strOriginal.Length - 1
            MessageBox.Show(strOriginal(i).ToString())
      Next i

For Each Loop in VB.Net

For Each c As Char In strOriginal
            MessageBox.Show(c.ToString())
Next c

 

Split a String

String.Split() can be used to split strings. The method takes a array of chars that represent characters that are to be used as delimiters. We're going to split the strOriginal string using 'space' as a delineator.

Split string in C#

char[] del = {' '};
    string[] strArr = strOriginal.Split(del);
    foreach (string s in strArr)
    {
        MessageBox.Show(s);
    }

Split string in VB.Net

 Dim delim As Char() = {" "c}
 Dim strArr As String() = strOriginal.Split(delim)
    For Each s As String In strArr
            MessageBox.Show(s)
      Next s

 

Extract Substrings

The String.Substring() gets a substring from a string starting from a specified position of the character. We can specify the length, too.

SubStrings in C#

// only starting position specified
    strModified = strOriginal.Substring(10);
    MessageBox.Show(strModified);
 
    // starting position and length of string to be extracted specified
    strModified = strOriginal.Substring(10, 3);
    MessageBox.Show(strModified);

SubStrings in VB.Net

' only starting position specified
      strModified = strOriginal.Substring(10)
      MessageBox.Show(strModified)
 
      ' starting position and length of string to be extracted specified
      strModified = strOriginal.Substring(10, 3)
      MessageBox.Show(strModified)

 

String Array

We can create different type of string array. There are  two type of string array Single Dimensional and Multi Dimensional arrays. Let's look at some of them

Single Dimensional String Array in C#

// Single Dimensional String Array
 
    string[] strArr = new string[3] { "string 1", "string 2", "string 3"};
    // Omit Size of Array
    string[] strArr1 = new string[] { "string 1", "string 2", "string 3" };
    // Omit new keyword
    string[] strArr2 = {"string 1", "string 2", "string 3"};

Multi Dimensional String Array in C#

// Multi Dimensional String Array
 
    string[,] strArr3 = new string[2, 2] { { "string 1", "string 2" }, { "string 3", "string 4" } };
    // Omit Size of Array
    string[,] strArr4 = new string[,] { { "string 1", "string 2" }, { "string 3", "string 4" } };
    // Omit new keyword
    string[,] strArr5 = { { "string 1", "string 2" }, { "string 3", "string 4" } };
 

Single Dimensional String Array in VB.Net

' Single Dimensional String Array
 
      Dim strArr As String() = New String(2) { "string 1", "string 2", "string 3"}
      ' Omit Size of Array
      Dim strArr1 As String() = New String() { "string 1", "string 2", "string 3" }
      ' Omit new keyword
      Dim strArr2 As String() = {"string 1", "string 2", "string 3"}

Multi Dimensional String Array in VB.Net

' Multi Dimensional String Array
 
      Dim strArr3 As String(,) = New String(1, 1) { { "string 1", "string 2" }, { "string 3", "string 4" } }
      ' Omit Size of Array
      Dim strArr4 As String(,) = New String(, ) { { "string 1", "string 2" }, { "string 3", "string 4" } }
      ' Omit new keyword
      Dim strArr5 As String(,) = { { "string 1", "string 2" }, { "string 3", "string 4" } }
 

 

Reverse a String

Using the StrReverse() function is one of the simplest ways to reverse a string. We must add a reference to the Microsoft.VisualBasic dll to use it in C#.

Reverse a String in C#

string strModified = Microsoft.VisualBasic.Strings.StrReverse(strOriginal);
    MessageBox.Show(strModified);

Reverse a String in VB.Net

Dim strModified As String = StrReverse(strOriginal)
      MsgBox(strModified)

 

 

Compare Two Strings

We can compare two strings using the String.Compare() methos. The third parameter is Boolean, which determines whether or not the search is case sensitive.

Compare Two String in C#

if ((string.Compare(strOriginal, strModified, false)) < 0)
    {
        MessageBox.Show("strOriginal is less than strOriginal1");
    }
    else if ((string.Compare(strOriginal, strModified, false)) > 0)
    {
        MessageBox.Show("strOriginal is more than strOriginal1");
    }
    else if ((string.Compare(strOriginal, strModified, false)) == 0)
    {
        MessageBox.Show("Both strings are equal");
    }

Compare Two String in VB.Net

 If (String.Compare(strOriginal, strModified, False)) < 0 Then
            MessageBox.Show("strOriginal is less than strOriginal1")
      ElseIf (String.Compare(strOriginal, strModified, False)) > 0 Then
            MessageBox.Show("strOriginal is more than strOriginal1")
      ElseIf (String.Compare(strOriginal, strModified, False)) = 0 Then
            MessageBox.Show("Both strings are equal")
      End If

 

Convert a String to Byte[] or Byte Array

The Encoding.GetBytes() encodes all the characters into a sequence of bytes. The method consists of six overloads from which we use the. GetBytes(string) encoding.

Convert string in Byte[] in C#

byte[] b = Encoding.Unicode.GetBytes(strOriginal);

Convert string in Byte[] in VB.Net

Dim b As Byte() = Encoding.Unicode.GetBytes(strOriginal)

Note: Depending upon your requirement, we can adopt various encoding schemes (ASCII, Unicode, etc.).

 

Convert Byte[] to String

The Encoding.GetString() decodes a sequence of bytes into a string.

Convert Byte[] to string in c#

// Assuming you have a Byte Array byte[] b
    strModified = Encoding.Unicode.GetString(b);

Convert Byte[] to string in VB.Net

' Assuming you have a Byte Array byte[] b
      strModified = Encoding.Unicode.GetString(b)

 

Convert a String to Char[] or Char Array

Use the String.ToCharArray() which copies the characters in the string to Unicode character array, to convert a string to char array.

Convert a string to char[] in C#

 char[] chArr = strOriginal.ToCharArray();

Convert a string to char[] in VB.Net

 Dim chArr As Char() = strOriginal.ToCharArray()

 

Convert a Char[] to String

The String Constructor which accepts a character array is an easy way to convert a character array to a string

Convert a Char[] to string C#

strModified = new String(chArr);

Convert a Char[] to string VB.Net

strModified = New String(chArr)

 

String is null or Zero Length

The String.IsNullOrEmpty(String), which returns a boolean value, shall be used if a string is null or empty.

String is null or Zero Length in C#

bool check = string.IsNullOrEmpty(strOriginal);

String is null or Zero Length in C#

Dim check As Boolean = String.IsNullOrEmpty(strOriginal)

 

Convert the Case of a String

The Class String contains methods for converting a string into lower and upper cases. However, a method for converting a string to a suitable case / title case is missing. We are therefore going to do the same with the TextInfo class.

Convert the case of string in C#

System.Globalization.CultureInfo cultureInfo = System.Threading.Thread.CurrentThread.CurrentCulture;
    System.Globalization.TextInfo textInfo = cultureInfo.TextInfo;
    // Lower Case
    MessageBox.Show(textInfo.ToLower(strOriginal));
    // Upper Case
    MessageBox.Show(textInfo.ToUpper(strOriginal));
    // Proper Case
    MessageBox.Show(textInfo.ToTitleCase(strOriginal));

Convert the case of string in VB.Net

Dim cultureInfo As System.Globalization.CultureInfo = System.Threading.Thread.CurrentThread.CurrentCulture
      Dim textInfo As System.Globalization.TextInfo = cultureInfo.TextInfo
      ' Lower Case
      MessageBox.Show(textInfo.ToLower(strOriginal))
      ' Upper Case
      MessageBox.Show(textInfo.ToUpper(strOriginal))
      ' Proper Case
      MessageBox.Show(textInfo.ToTitleCase(strOriginal))

 

Count the occurrences of words in a String

We can take several ways to find a word's occurrence in a string.One of the ways to find the occurence of the word is by using the String.IndexOf(). String.InStr() is used in VB.NET.

Another easy way to use Regex.Matches() collection's Counter property. But this is a slow procedure. These two methods are to be explored in the sample.

Count the occurrence of word in C#

// Using IndexOf
     int strt = 0;
     int cnt = -1;
     int idx = -1;
     strOriginal = "Uttarakhand, a state in northern India";
     string srchString = "state";
     while (strt != -1)
     {
         strt = strOriginal.IndexOf(srchString, idx + 1);
         cnt += 1;
         idx = strt;
     }
     MessageBox.Show(srchString + " occurs " + cnt + " times");
 
 
    // Using Regular Expression
    System.Text.RegularExpressions.Regex rex = new System.Text.RegularExpressions.Regex(srchString);
    int count = rex.Matches(strOriginal).Count;
    MessageBox.Show(srchString + " occurs " + count + " times");

Count the occurrence of word in VB.Net

' Using IndexOf
       Dim strt As Integer = 0
       Dim cnt As Integer = -1
       Dim idx As Integer = -1
       strOriginal = "Uttarakhand, a state in northern India"
       Dim srchString As String = "state"
       Do While strt <> -1
             strt = strOriginal.IndexOf(srchString, idx + 1)
             cnt += 1
             idx = strt
       Loop
       MessageBox.Show(srchString & " occurs " & cnt & " times")
 
 
      ' Using Regular Expression
       Dim rex As System.Text.RegularExpressions.Regex = New System.Text.RegularExpressions.Regex(srchString)
      Dim count As Integer = rex.Matches(strOriginal).Count
      MessageBox.Show(srchString & " occurs " & count & " times")

 

 

Insert Characters inside a String

In a certain Index location, the String.insert() inserts text. At a given index position we can insert any character or string. For example: we insert "very" in the string strOriginal at index 26.

Insert characters inside string in C#

strModified = strOriginal.Insert(10, "common");
    MessageBox.Show(strModified);

Insert characters inside string in VB.Net

strModified = strOriginal.Insert(10, "common")
MessageBox.Show(strModified)

 

Replace characters in a String

String.Replace() removes strings and substitutes them with a new character or string.

Replace character in string in C#

strModified = strOriginal.Replace("are", "are common");
    MessageBox.Show(strModified);

Replace character in string in VB.Net

strModified = strOriginal.Replace("are", "are common")
      MessageBox.Show(strModified)

We will explore several other string operations commonly used in projects in the following article.

 

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Common String Operations