C ＃ getting started series (12) -- string

String Overview

stay  C#  in , You can use character arrays to represent strings , however , A more common practice is to use  string  Keyword to declare a string variable .string  Keywords are  System.String  Alias of class .

String Class represents text , A series of Unicode character . In namespace system in .

String The members provided by the class do the following ： Compare String object ; return String The index of a character or string within an object ; Copy String The value of the object ; Separate or combine strings ; Modify the value of the string ; The digital 、 The date and time or enumeration value is formatted as a string ; Normalize strings .

String common properties

String  Class has two properties ：

• Chars： Get current String The character at the specified character position in the object .

• Length： Get current String The number of characters in the object .

class Program
{
 static void Main(string[] args)
 {
 string str = " I'm a string ";

 Console.WriteLine(str[0]); //  Output ： I
 Console.WriteLine(str.Length); //  Output ：7

 Console.ReadLine();
 }
}


String common methods

• Compare Method
  ：Compare There are many ways to overload , Implement two strings according to the specified rules 、 The comparison operation of the specified range , Method returns an integer , Used to describe the relative position in the sorting of two strings .

• Concat Method
  ：Concat There are many ways to overload , Realize the connection operation of the specified string or object .

• Contains Method
  ： Returns a Boolean value , This value represents the specified String Whether the object appears in this string .

• EndsWith Method ：
  ： Returns a Boolean value , Determines whether the end of this string instance matches the specified string .

• StartsWith Method ：
  ： Returns a Boolean value , To determine whether the string starts with the specified substring .

• Equals Method
  ：Equals Methods can be overloaded in many ways , The implementation determines two according to certain rules String Whether the instance has the same value .

• Format Method
  ：Format Methods can be overloaded in many ways , Replaces one or more format items in the specified string with the string representation of the specified object .

• IndexOf Method
  ：IndexOf Methods can be overloaded in many ways , Reports the index of the first occurrence of a specified character or string within a specified range in this instance .

• and 8 A similar approach is ：IndexOfAny,LastIndexOf, LastIndexOfAny Other methods , Reports the index of a match of a specified character or string within a specified range in this instance .

• Insert Method
  ：Insert Method inserts a specified index at the specified index position in this instance String example .

• Remove Method
  ：Remove Method to delete the character specified in this instance .

• **Replace Method ：**Replace Method to replace the character or substring specified in this instance .

• **Split Method ：**Split There are many ways to overload , Realize the function of dividing the string according to the specified characters to form multiple substrings .

• Substring Method
  ：Substring There are two ways to overload , Realize the function of substring the string according to the specified starting position and specified length .

• ToLower Methods and ToUpper Method
  ： Converts characters in a string to lowercase , Or convert to uppercase .

• Trim Method
  ： Delete all leading and trailing white space characters in the string . There is also “TrimStart” and “TrimEnd”  They are the blank characters before and after deleting the string