Common properties and methods for strings in C #

This article is a summary of the properties and methods we commonly use for string types in C #:

"1" Construction Method:

By constructing a method, we can build a string variable (or an object instance of string type) according to our own needs.

Case 1) by constructing a method, declaring and assigning a string consisting of 20 characters ' H ' and outputting it.

Code:

String Str=new string (' H ', 20); Creates a new object of type string and constructs a 20-h string with a constructor method (function) and assigns it to STR

Console.WriteLine (STR);

Console.readkey ();

Execution results:

Case 2) by constructing the method, constructs a character array {' H ', ' e ', ' l ', ' l ', ' o ', ', ', ', ', ', ', ', ', ', ', ', ', ', ', ', ' O ', ' r ', ' L ', ' d '

String Str=new string (new char[]{' H ', ' e ', ' l ', ' l ', ' l ', ' o ', ', ', ' W ', ' o ', ' r ', ' L ', ' d '});

Console.WriteLine (STR);

Console.readkey ();

Execution results:

"2" Length property to get the number of characters for the string.

Case 1) Gets the string "Hello,world." "Number of characters.

String str= "hello,world!";

Console.WriteLine ("\" hello,world!\ "number of characters: {0}", str.length);

Console.readkey ();

Execution results:

The "3" ToUpper () method, in which all lowercase letters in the string are converted to uppercase.

Case 1) The string "hello,world!" Converts a lowercase letter in uppercase and outputs a converted string.

String str= "hello,world!";

String Strnew=str.toupper ();

Console.WriteLine ("The string before conversion is: {0}", STR);

Console.WriteLine ("The converted string is: {0}", strnew);

Console.readkey ();

Execution results:

The "4" ToLower () method, in which all uppercase letters in a string are converted to lowercase.

Case 1) The string "hello,world!" Converts lowercase letters to uppercase and outputs the converted string.

String str= "hello,world!";

String Strnew=str.tolower ();

Console.WriteLine ("The string before conversion is: {0}", STR);

Console.WriteLine ("The converted string is: {0}", strnew);

Console.readkey ();

Execution results:

"5" compares two strings for the same, and you can select the comparison mode by parameter (case-insensitive or case-sensitive).

Case 1) Compare two string "hello,world!" in case-insensitive mode and "hello,world!".

String str1= "hello,world!";

String str2= "hello,world!";

case-insensitive mode

if (Str1.equals (str2,stringcomparison.ordinalignorecase))

{

Console.WriteLine ("The two strings that are compared are the same. ");

}

Else

{

Console.WriteLine ("The two strings compared are not the same. ");

}

Console.readkey ();

Execution results:

Case 2) Compare two string "hello,world!" in case-sensitive mode and "hello,world!".

String str1= "hello,world!";

String str2= "hello,world!";

case-sensitive mode

if (Str1.equals (str2,stringcomparison.ordinal))

{

Console.WriteLine ("The two strings that are compared are the same. ");

}

Else

{

Console.WriteLine ("The two strings compared are not the same. ");

}

Console.readkey ();

Execution results:

The "6" split () method, which splits the string, returns an array of string types.

Case 1) Split string "I am &c* #初 (Learn |) to form a" I am a C # beginner "string.

String str= "I am &c* #初 (Learn |);

Char[] chr={', ' & ', ' (', ' | ', '; '};

string[] strnew = Str.split (Chr, stringsplitoptions.removeemptyentries); The split string makes up a string array and removes the empty string

String str1= "";

for (int i=0;i<strnew.length;i++)

{

Str1+=strnew[i];

}

Console.WriteLine ("The string you want to get is: {0}", STR1);

Console.readkey ();

Execution results:

The "7" Substring () method intercepts the string and includes the indexed location at the time of interception.

Case one) intercept string "Everyone good, I am a C # beginner" in the "I am a C # beginner", and output before and after the interception of the string.

String strold= "Everybody good, I am a C # beginner";

String strnew=strold.substring (4);

Console.WriteLine ("The string before the interception is: {0}", Strold);

Console.WriteLine ("The string after the interception is: {0}", strnew);

Console.readkey ();

Execution results:

The "8" IndexOf () method is used to determine the index of the position of the first occurrence of a string in the string, and no return-1.

Case 1) Look for "C #" in, "Hello everyone, I am a C # beginner." "The position in the string. (in the first few characters).

String str1= "Hello everyone, I am a C # beginner." ";

int Position;

Position=str1.indexof ("C #");

Position+=1;

Console.WriteLine ("\" c#\ "in \" Everybody good, I am a C # beginner. \ {0} location. ", Position);

Console.readkey ();

Execution results:

The "9" LastIndexOf () method determines the index of the last occurrence of a string in the string, and returns 1.

Case 1 Output string "C #" in string "I love C #, you love C #, we all love C # language." The last occurrence in the.

String str= "I love C #, you love C #, we all love the C # language." ";

int Position;

Position=str.lastindexof ("C #");

Position+=1;

Console.WriteLine ("\" c#\ "in \" I love C #, you love C #, we all love C # language.) \ "Location {0}" appears, Position);

Console.readkey ();

Execution results:

"10" Determines whether the string starts with the specified substring.

Case 1) Judged "Everyone good, I am a C # beginner." Whether to start with "Everyone good", if it is the output is, if not the output is not.

String str= "Hello everyone, I am a C # beginner." ";

if (Str.startswith ("everyone good"))

{

Console.WriteLine ("Yes");

}

Else

{

Console.WriteLine ("not");

}

Console.readkey ();

Execution results:

"11" Determines whether the string ends with the specified substring.

Case 1) Judged "Everyone good, I am a C # beginner." "Whether the string is to". End

String str= "Hello everyone, I am a C # beginner." ";

if (Str.endswith) (". "))

{

Console.WriteLine ("Yes");

}

Else

{

Console.WriteLine ("not");

}

Console.readkey ();

Execution results:

"12" replaces the substring specified in the string with the string you want.

Case 1) will "everyone good, I am a C # beginner." "In the string." "Replace with". ”。

String str= "Hello everyone, I am a C # beginner." ";

String Strnew=str.replace (". ","。 ");

Console.WriteLine ("The string before substitution is: {0}", STR);

Console.WriteLine ("The replaced string is: {0}", strnew);

Console.ReadLine ();

Execution results:

The "13" Contains () method to determine whether the string contains the specified substring.

Case 1) to judge the string "Everyone good, I am a C # beginner." "String contains the substring" C # "If it contains the output" contains "if the output" does not contain "is not included.

String str= "Hello everyone, I am a C # beginner." ";

if (Str.contains ("C #"))

{

Console.WriteLine ("included.") ");

}

Else

{

Console.WriteLine ("not included.") ");

}

Console.readkey ();

Execution results:

"14" Trim () method, remove the space before and after the string.

Case 1) Remove the front and back spaces of the string "I am a C # beginner".

String Str= "I am a C # beginner";

String Strnew=str.trim ();

Console.WriteLine ("The string to remove before and after spaces is: {0}", STR);

Console.WriteLine ("Remove the string after the front and back space is: {0}", strnew);

Console.readkey ();

Execution results:

The "15" TrimStart () and TrimEnd () methods are to remove the space before the string and remove the space after the string.

Case 1) Remove "I am a C # beginner" and output separately.

String Str= "I am a C # beginner";

String Str1=str.trimstart ();

Console.WriteLine ("Remove the previous string as: {0}", STR);

Console.WriteLine ("Remove the space before the string: {0}", STR1);

String Str2=str1.trimend ();

Console.WriteLine ("Remove the space following the string: {0}", STR2);

Console.readkey ();

Execution results:

"16" string. IsNullOrEmpty () method to determine whether a string is empty.

Case 1) to determine if the "Hello" string is empty.

String str= "Hello";

if (string. IsNullOrEmpty (STR))

{

Console.WriteLine ("String is empty");

}

Else

{

Console.WriteLine ("String is not null");

}

Console.readkey ();

Execution results:

"17" string. Join () method, which joins the array in the specified string and returns a string.

Case 1, the string array {"Big", "Home", "good"} output as "big | home | good" form.

String[] str={"Big", "Home", "good"};

String strnew=string. Join ("|", STR);

Console.WriteLine (strnew);

Console.readkey ();

Execution results: