C # string processing

In C # programming, there are many measures to deal with strings, such as removing the whitespace "trim" at both ends of the string, removing the character ' 0 ' at both ends of the string, and giving the string a certain length of "padleft,padright" and so on.

Since this time the project is used more, based on this, the string of some common things to summarize.

Use STR to represent a string.

1. Length of the string :

Str. Length;

2. Get each character in the string:

Here it is necessary to speak of a function, just seen, quite excited, ToCharArray (), function said below.

A string type variable can be considered a read-only group of char variables, so you can

To get each character in a character array by ToCharArray (), here's a small example: string str= "I am a student";
char[] MyChar = str. ToCharArray ();

3. Case conversion of characters in a string:

Str. ToLower (); Str. ToUpper ().

4. Whitespace in the string, etc.

Str. Trim (); Remove all the leading and trailing spaces of the string (not including the middle). You can also delete other characters, as long as you specify them in a char array. Give me a small example.

1       string str="   "; 2       Char [] trimchars={','t','I' }; 3       str = Str. Trim (TrimChars); 4       Console.WriteLine (str);       

Output: AM A Studen

Trim () only removes all the characters that are drawn from the string.

TrimStart (), TrimEnd (), similar to trim ().

Here are two ways to add a space, str. PadLeft (); Str. PadRight (), there are two overloaded methods.

Str. PadLeft (20), specifying the length of the new string as 20,str. PadLeft (20, ' # '), in addition to the specified length, the number of digits is not enough to fill with ' # '. These two methods are used to align strings.

5. String comparison size:

String.Compare (str1, str2);

This is not the comparison length, the return value has three, STR1>STR2, the result is 1;< result for the -1;= result is 0. "Stu" > "Stu". If you only compare two strings for equality, use STR1. Equals (STR2), which returns true and false.

6. Find whether a string contains the specified string.

public bool Contains (string str1); Example: if (str. Contains ("abc")) {...}

7. Find the position of a character or substring that appears in the string.

1   string str="student"; 2 3    Str. IndexOf ("tu"
     Str. IndexOf ("t"
     Str. IndexOf ('t');

The return value is all 1.

Another overloaded mode: public int IndexOf (string str,int startIndex);

If these two methods are not found, the return value is-1.

The LastIndexOf () usage is the same as indexof (), except that the lookup is in the opposite direction, but still from the front.

such as: int i= str. LastIndexOf (' n '); The value of I is 5.

8. intercept the string:

Two kinds of overloaded methods

1, str. Substring (3); A parameter indicates that the character from Subscript 3 begins to intercept to the last.

2, str. Substring (1,3); two parameters indicate starting with a character subscript 2, and intercepting a substring of length 3.

9. Inserting, deleting, and replacing strings.

Insert: public string Insert (int startindex,string value); There is only one way to overload it.

Delete: public string remove (int startIndex); Removes characters from startindex to the end.

The public string, remove (int startindex,int count), removes the character starting from StartIndex with a length of count.

Replace: public string Replace (string oldstring,string newstring);

public string Replace (char OldChar, char Newchar);

10. String merging, this is not used much.

1  string [] arr={"I","am","a",  "student"}; 2  Console.WriteLine (string. Join ("@", arr));

Output:[email protected]@[email protected]

11.Split () method . This is a lot of use.

Public string[] Split (char[] separator);

1. Delimited by string:

1 usingSystem.Text.RegularExpressions;2 stringStr="AAAJSBBBJSCCC";3 string[] Sarray=regex.split (str,"JS", regexoptions.ignorecase);4 foreach(stringIinchSarray) Response.Write (i.tostring () +"<br>");

Output Result:
Aaa
Bbb
Ccc

2, separated by multiple characters:

1 stringStr="aaajbbbscccjdddseee"; 2 string[] sarray=str. Split (New Char[2] {'J','s'}); 3 foreach(stringIinchSarray) Response.Write (i.tostring () +"<br>");

Output Result:
Aaa
Bbb
Ccc
Ddd
Eee
3. Separate the characters with a single character:

1 string str="aaajbbbjccc"; 2 string [] sarray=str. Split ('J'); 3 foreach (stringin"<br>");

Output Result:
Aaa
Bbb
Ccc

C # string processing