C # string processing

1. Comparing Strings

The String class provides a series of methods for string comparisons, such as the CompareTo and equals methods.

　　①compareto:

Returns 0 if the value of the argument is equal to this instance, or 1 if this instance is greater than the value of the parameter; otherwise returns-1.

String str1 = "abc";

int m1 = Str1.compareto ("abc"); M1 = 0

int m2 = str1.compareto ("ab"); M2 = 1

int m3 = Str1.compareto ("ABCD"); M3 =-1

　　②equals

True if the value of the parameter is the same as this instance; otherwise false.

String str1 = "abc", STR2 = "abc", STR3 = "abc";

BOOL B1 = str1. Equals (STR2); False

BOOL B2 = str1. Equals (STR3);//true

Note: The Equals method is case-sensitive.

　2. Locating characters and substrings

Position the first occurrence of a character or substring in a string using the IndexOf method.

If the character is found, the index position is the value of the parameter, starting at 0, or 1 if the character is not found, or 0 if the argument is empty.

String str1 = "ABCD";

int m1 = str1. IndexOf ("B"); 1

int m2 = str1. IndexOf ("CD");//2

int m3 = str1. IndexOf (""); 0

int m4 = str1. IndexOf ("w");//-1

　　3. Formatting strings

Format to currency type

String str1 = String.Format ("(C) currency:{0:c}\n", -123.45678f); (C) currency:￥-123.46

Format to ShortDate type

String str2 = String.Format ("(d) Short date:{0:d]\n", DateTime.Now); (d) Short DATE:2009/11/6

　　4. Intercepting strings

String str = "Hello world!";

String str1 = str. Substring (0,5);//Hello

The first parameter represents the starting position of the substring, and the second parameter represents the length of the substring.

　　5. Split string

The Split method splits a string into a series of small strings according to a delimiter.

String str = "hello.world!";

string[] spilt = str. Split ('. ', '! ');

foreach (string s in spilt)

{

if (S.trim ()! = "")

Console.WriteLine (s);

}

　　6. Inserting and populating strings

　　① inserting a string

String str = "This is a girl";

str = str. Insert (Ten, "Beautiful");//This is a beautiful girl

The first parameter specifies the position to insert, the index starts at 0, and the second parameter specifies the string to insert.

　② padding string

String str = "Hello world!";

String str1 = str.  PadLeft (15, ' @ '); @@ ZZFCTHOTFIXZ world!

String str2 = str.  PadRight (15, ' @ '); Hello [Email protected]@@

The first parameter specifies the length of the string after the fill, and the second parameter specifies the character to be populated. The second argument can be omitted, and if omitted, the space symbol is filled.

　　7. Delete and cut strings

　　① Deleting a string

String str = "This is a beautiful girl.";

str = str. Remove (10,10); This is a girl.

The first parameter specifies where to start the deletion, the index starts at 0, and the second parameter specifies the number of characters to delete.

　　② clipping string

String str = "*_*hello world! *_*";

String str1 = str. TrimStart (new char[] {' * ', ' _ '});//hello world! *_*

String str2 = str. TrimEnd (new char[] {' * ', ' _ '});//*_*hello world!

　8. Copying strings

String str= "It is a dog";

String newstr=string.copy (str);

　9. Replace string

String str= "It is a dog";

Str=str. Replace ("Dog", "pig");

　10. Determine if the string is empty

string str = "AA";

BOOL B = String.IsNullOrEmpty (str);

　　11. Determine if the string contains Chinese

String str = "AAAAA";

BOOL B = Regex.IsMatch (str, @ "[\u4e00-\u9fa5]");

12. Determine if a string contains another string

String str1 = "Hello!" XXXX ";

String str2 = "Hello";

BOOL B = str1. Contains (STR2);

C # string processing