C # basic knowledge record 1,

C # basic knowledge record 1,

 

C # basic knowledge record 1

Static void Main (string [] args)

{

# Use of region merge operators (merge operators ??) For more operators, see https://msdn.microsoft.com/zh-cn/library/ms173224 (v = vs.100). aspx

Int? X = null;

 

// Write the merge Operator

Int? Y = x ?? 0;

// Statement of the ternary OPERATOR:

Y = x = null? 0: x;

Console. WriteLine (y );

 

# Endregion

 

# Region multi-dimensional array reference MSDN: https://msdn.microsoft.com/zh-cn/library/2yd9wwz4 (v = vs.80). aspx

// Two-dimensional array (3 rows and 3 columns)

Int [,] array2 = new int [3, 3];

Int [,] arr2 = {1, 2}, {2, 3}, {4, 5 }};

Int [,] arr3 = {1, 2, 3 },{ 2, 3, 4 }},{ 4, 5, 6 }}};

Foreach (var item in arr3)

{

Console. Write (item );

}

// 3D array:

Int [,] array3 = new int [3, 3, 3];

// Sawtooth array (more flexible ):

Int [] [] juarray = new int [3] [];

Juarray [0] = new int [2] {1, 2 };

// Nested cyclic sawtooth array:

For (int I = 0; I <juarray. Length; I ++)

{

If (juarray [I]! = Null)

For (int j = 0; j <juarray [I]. Length; j ++)

{

Console. WriteLine ("value: {0}", juarray [I] [j]);

}

}

Console. WriteLine (juarray [0] [0]);

 

# Endregion

 

# Region string Regular Expression

// ------ Basic ----------------

/* Metacharacters:.: match any character other than line breaks \ B: match the start or end of a word \ d: Match Number \ s: match any blank character

* ^: Start of matching string $: End of matching string

* Qualifier: *: Repeated 0 or multiple times +: repeated once or multiple times? : Repeated 0 times or 1 time {n}: Repeated n times {n,}: Repeated n times or more times

* {N, m}: Repeat n to m times

*