本文主要介紹C#最基本要件和運算式,以供有興趣的朋友參考。


Statements
StatementC#最基本的組成,所有程式都是由Statement建構的,可以宣告區域變數、常數、呼叫方法、建立物件,或指派值給變數、屬性或欄位。
Statement通常以分號結尾。
 
常見的Statements
分類
C# 關鍵字
Declaration statements
xx=2
Expression statements
area = 3.14 * (radius * radius);
Selection statements
ifelseswitchcase
Iteration statements
doforforeachinwhile
Jump statements
breakcontinuedefaultgotoreturnyield
Exception handling statements
throwtry-catchtry-finallytry-catch-finally
 
Msdn Example:
    static void Main()
    {
        // Declaration statement.
        int counter;
 
        // Assignment statement.
        counter = 1;
 
        // Error! This is an expression, not an expression statement.
        // counter + 1; 
 
        // Declaration statements with initializers are functionally
        // equivalent to pointA declaration statement followed by assignment statement:         
        int[] radii = { 15, 32, 108, 74, 9 }; // Declare and initialize an array.
        const double pi = 3.14159; // Declare and initialize pointA constant.          
 
        // foreach statement block that contains multiple statements.
        foreach (int radius in radii)
        {
            // Declaration statement with initializer.
            double circumference = pi * (2 * radius);
 
            // Expression statement (method invocation). A single-line
            // statement can span multiple text lines because line breaks
            // are treated as white space, which is ignored by the compiler.
            System.Console.WriteLine("Radius of circle #{0} is {1}. Circumference = {2:N2}",
                                    counter, radius, circumference);
 
            // Expression statement (postfix increment).
            counter++;
 
        } // End of foreach statement block
    } // End of Main method body.
} // End of SimpleStatements class.
 
Expression
運算式是程式碼片段,可判定為單一的值、物件、方法或命名空間。
運算式可包含常值、方法引動過程、運算子和運算元,或「簡單名稱」(Simple Name)。簡單名稱可以是變數的名稱、型別成員、方法參數、命名空間或型別。
 
Msdn example:
((x < 10) && ( x > 5)) || ((x > 20) && (x < 25))
System.Convert.ToInt32("35")
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