C # Summary of the Operation string method & lt; Convert & gt ;,

C # Summary of the Operation string method <>,

Staticvoid Main (string [] args)
{
String s = "";
// (1) character access (subscript access s [I])
S = "ABCD ";
Console. WriteLine (s [0]); // output "";
Console. WriteLine (s. Length); // output 4
Console. WriteLine ();

// (2) scatter as a character array (ToCharArray)
S = "ABCD ";
Char [] arr = s. ToCharArray (); // splits the string into character arrays {'A', 'B', 'C', 'D '}
Console. WriteLine (arr [0]); // outputs the first element of the array and outputs ""
Console. WriteLine ();

// (3) extract the Substring (Substring)
S = "ABCD ";
Console. WriteLine (s. Substring (1); // truncate from 2nd bits (index starts from 0) until the end of the string, and output "BCD"
Console. WriteLine (s. Substring (1, 2); // truncates two digits from the first digit and outputs "BC"
Console. WriteLine ();

// (4) matching index (IndexOf ())
S = "ABCABCD ";
Console. WriteLine (s. IndexOf ('A'); // search for the position index of the First Matching character A from the string header, and output "0"
Console. WriteLine (s. IndexOf ("BCD"); // search for the position of the first matching string BCD from the string header, and output "4"
Console. WriteLine (s. LastIndexOf ('C'); // search for the position of the First Matching character C from the end of the string, and output "5"
Console. WriteLine (s. LastIndexOf ("AB"); // search for the position of the first BCD matching string starting from the end of the string, and output "3"
Console. WriteLine (s. IndexOf ('E'); // search for the first matching string E position starting from the string header without matching the output "-1 ";
Console. WriteLine (s. Contains ("ABCD"); // checks whether another string "ABCD" exists in the string and outputs true
Console. WriteLine ();

// (5) Case sensitivity conversion (ToUpper and ToLower)
S = "aBcD ";
Console. WriteLine (s. ToLower (); // converts it to lowercase and outputs "abcd"
Console. WriteLine (s. ToUpper (); // convert to uppercase and output "ABCD"
Console. WriteLine ();

// (6) Fill alignment (PadLeft and PadRight)
S = "ABCD ";
Console. writeLine (s. padLeft (6, '_'); // use '_' to fill the left of the string and extend it to the total length of 6 characters. The output is "_ ABCD"
Console. writeLine (s. padRight (6, '_'); // use '_' to fill the right of the string and extend it to the total length of 6 bits. The output is "ABCD __"
Console. WriteLine ();

// (7) truncation and removal (Trim)
S = "_ AB __CD __";
Console. WriteLine (s. Trim ('_'); // remove the '_' character from the header and tail of the string and output "ABCD cd"
Console. WriteLine (s. TrimStart ('_'); // remove the '_' character from the header of the string and output "abcd cd __"
Console. WriteLine (s. TrimEnd ('_'); // remove the '_' character at the end of the string and output "_ ABCD cd"
Console. WriteLine ();

// (8) Insert and delete (Insert and Remove)
S = "ADEF ";
Console. WriteLine (s. Insert (1, "BC"); // Insert the string "BC" at the 2nd-bit position of the string and output "ABCDEF"
Console. WriteLine (s );
Console. WriteLine (s. Remove (1); // delete all the characters starting from the second character of the string and output ""
Console. WriteLine (s );
Console. WriteLine (s. Remove (0, 2); // Delete two characters starting from the 1st bits of the string and output "EF"
Console. WriteLine ();

// (9) Replace character (string) (Replace)
S = "A_ B _C_D ";
Console. WriteLine (s. Replace ('_', '-'); // Replace the '_' character in the string with '-', and output "A-B-C-D"
Console. WriteLine (s. Replace ("_", ""); // Replace "_" in the string with an empty string and output "a B C D"
Console. WriteLine ();

// (10) Split into a String Array (Split) -- reciprocal operation: Join a string static method (seperator, arr [])
S = "AA, BB, CC, DD ";
String [] arr1 = s. Split (','); // use the ',' character to separate the string and return an array of strings.
Console. WriteLine (arr1 [0]); // output "AA"
Console. WriteLine (arr1 [1]); // output "BB"
Console. WriteLine (arr1 [2]); // output "CC"
Console. WriteLine (arr1 [3]); // output "DD"
Console. WriteLine ();

S = "AA--BB--CC--DD ";
String [] arr2 = s. replace ("--","-"). split ('-'); // string-based splitting technique: First Replace the string "--" with a single character "-", then, the string is separated by the '-' character and an array of strings is returned.
Console. WriteLine (arr2 [0]); // output "AA"
Console. WriteLine (arr2 [1]); // output "BB"
Console. WriteLine (arr2 [2]); // output "CC"
Console. WriteLine (arr2 [3]); // output "DD"
Console. WriteLine ();

// (11) Format (static Format)
Console. WriteLine (string. Format ("{0} + {1} = {2}", 1, 2, 1 + 2 ));
Console. WriteLine (string. Format ("{0}/{1} = {. 000}", 1, 3, 1.00/3.00 ));
Console. WriteLine (string. Format ("{0: MM dd, yyyy}", DateTime. Now ));


// (12) connect to a string (static method Concat, static method Join, and instance method StringBuilder. Append)
S = "A, B, C, D ";
String [] arr3 = s. Split (','); // arr = {"A", "B", "C", "D "}

Console. WriteLine (string. Concat (arr3); // concatenates a string array into a string and outputs "ABCD"

Console. writeLine (string. join (",", arr3); // use "," as the separator to concatenate A string array into A string and output "A, B, C, D"

StringBuilder sb = new StringBuilder (); // declare a string constructor instance
Sb. Append ("A"); // use the string constructor to connect to the string for higher performance
Sb. Append ('B ');
Console. WriteLine (sb. ToString (); // output "AB"

Console. ReadKey ();
}