C#语句基础

C# 中的大多数语句都是直接从 C 和 C++ 借用的，但有一些值得注意的添加和修改。下表列出了可用的语句类型，并提供了每种类型的示例。

语句	示例
语句列表和块语句	static void Main() { F(); G(); { H(); I(); } }
标记语句和 goto 语句	static void Main(string[] args) { if (args.Length == 0) goto done; Console.WriteLine(args.Length); done: Console.WriteLine("Done"); }
局部常数声明	static void Main() { const float pi = 3.14f; const int r = 123; Console.WriteLine(pi * r * r); }
局部变量声明	static void Main() { int a; int b = 2, c = 3; a = 1; Console.WriteLine(a + b + c); }
表达式语句	static int F(int a, int b) { return a + b; } static void Main() { F(1, 2); // Expression statement }
if 语句	static void Main(string[] args) { if (args.Length == 0) Console.WriteLine("No args"); else Console.WriteLine("Args"); }
switch 语句	static void Main(string[] args) { switch (args.Length) { case 0: Console.WriteLine("No args"); break; case 1: Console.WriteLine("One arg "); break; default: int n = args.Length; Console.WriteLine("{0} args", n); break; } }
while 语句	static void Main(string[] args) { int i = 0; while (i < args.Length) { Console.WriteLine(args[i]); i++; } }
do 语句	static void Main() { string s; do { s = Console.ReadLine(); } while (s != "Exit"); }
for 语句	static void Main(string[] args) { for (int i = 0; i < args.Length; i++) Console.WriteLine(args[i]); }
foreach 语句	static void Main(string[] args) { foreach (string s in args) Console.WriteLine(s); }
break 语句	static void Main(string[] args) { int i = 0; while (true) { if (i == args.Length) break; Console.WriteLine(args[i++]); } }
continue 语句	static void Main(string[] args) { int i = 0; while (true) { Console.WriteLine(args[i++]); if (i < args.Length) continue; break; } }
return 语句	static int F(int a, int b) { return a + b; } static void Main() { Console.WriteLine(F(1, 2)); return; }
throw 语句和 try 语句	static int F(int a, int b) { if (b == 0) throw new Exception("Divide by zero"); return a / b; } static void Main() { try { Console.WriteLine(F(5, 0)); } catch(Exception e) { Console.WriteLine("Error"); } }
checked 和 unchecked 语句	static void Main() { int x = Int32.MaxValue; Console.WriteLine(x + 1); // Overflow checked { Console.WriteLine(x + 1); // Exception } unchecked { Console.WriteLine(x + 1); // Overflow } }
lock 语句	static void Main() { A a = ...; lock(a) { a.P = a.P + 1; } }
using statements	static void Main() { using (Resource r = new Resource()) { r.F(); } }