chap3.lst

Csharp2完全参考手册源代码 详细的说明可以在书里看到 该书是08年刚出炉很新鲜

listing 1
// Compute the distance from the Earth to the sun, in inches. 
 
using System; 
 
class Inches {    
  public static void Main() {    
    long inches; 
    long miles; 
   
    miles = 93000000; // 93,000,000 miles to the sun 
 
    // 5,280 feet in a mile, 12 inches in a foot 
    inches = miles * 5280 * 12; 
   
    Console.WriteLine("Distance to the sun: " + 
                      inches + " inches."); 
   
  }    
}

listing 2
// Use byte. 
 
using System; 
 
class Use_byte {    
  public static void Main() {    
    byte x; 
    int sum; 
 
    sum = 0; 
    for(x = 1; x <= 100; x++) 
      sum = sum + x; 
 
    Console.WriteLine("Summation of 100 is " + sum); 
  }    
}

listing 3
// Find the radius of a circle given its area. 
 
using System; 
 
class FindRadius {    
  public static void Main() {    
    Double r; 
    Double area; 
 
    area = 10.0; 
 
    r = Math.Sqrt(area / 3.1416); 
 
    Console.WriteLine("Radius is " + r); 
  }    
}

listing 4
//  Demonstrate Math.Sin(), Math.Cos(), and Math.Tan(). 
 
using System; 
 
class Trigonometry {    
  public static void Main() {    
    Double theta; // angle in radians 
     
    for(theta = 0.1; theta <= 1.0; theta = theta + 0.1) { 
      Console.WriteLine("Sine of " + theta + "  is " + 
                        Math.Sin(theta)); 
      Console.WriteLine("Cosine of " + theta + "  is " + 
                        Math.Cos(theta)); 
      Console.WriteLine("Tangent of " + theta + "  is " + 
                        Math.Tan(theta)); 
      Console.WriteLine(); 
    } 
 
  }    
}

listing 5
// Use the decimal type to compute a discount. 
  
using System;  
  
class UseDecimal {     
  public static void Main() {     
    decimal price;  
    decimal discount; 
    decimal discounted_price;  
  
    // compute discounted price 
    price = 19.95m;  
    discount = 0.15m; // discount rate is 15% 
 
    discounted_price = price - ( price * discount);  
  
    Console.WriteLine("Discounted price: $" + discounted_price);  
  } 
}

listing 6
/*   
   Use the decimal type to compute the future value 
   of an investment. 
*/   
   
using System; 
   
class FutVal { 
  public static void Main() { 
    decimal amount;   
    decimal rate_of_return;  
    int years, i;   
   
    amount = 1000.0M; 
    rate_of_return = 0.07M; 
    years = 10; 
 
    Console.WriteLine("Original investment: $" + amount); 
    Console.WriteLine("Rate of return: " + rate_of_return); 
    Console.WriteLine("Over " + years + " years"); 
 
    for(i = 0; i < years; i++) 
      amount = amount + (amount * rate_of_return); 
 
    Console.WriteLine("Future value is $" + amount);  
  } 
}

listing 7
// Demonstrate bool values. 
 
using System; 
 
class BoolDemo { 
  public static void Main() { 
    bool b; 
 
    b = false; 
    Console.WriteLine("b is " + b); 
    b = true; 
    Console.WriteLine("b is " + b); 
 
    // a bool value can control the if statement 
    if(b) Console.WriteLine("This is executed."); 
 
    b = false; 
    if(b) Console.WriteLine("This is not executed."); 
 
    // outcome of a relational operator is a bool value 
    Console.WriteLine("10 > 9 is " + (10 > 9)); 
  } 
}

listing 8
// Use format commands.  
 
using System; 
 
class DisplayOptions {    
  public static void Main() {    
    int i; 
 
    Console.WriteLine("Value\tSquared\tCubed"); 
 
    for(i = 1; i < 10; i++) 
      Console.WriteLine("{0}\t{1}\t{2}",  
                        i, i*i, i*i*i); 
  }    
}

listing 9
/*  
   Use the C format specifier to output dollars and cents.  
*/  
  
using System;  
  
class UseDecimal {     
  public static void Main() {     
    decimal price;  
    decimal discount; 
    decimal discounted_price;  
  
    // compute discounted price 
    price = 19.95m;  
    discount = 0.15m; // discount rate is 15% 
 
    discounted_price = price - ( price * discount);  
  
    Console.WriteLine("Discounted price: {0:C}", discounted_price);  
  }     
}

listing 10
// Demonstrate escape sequences in strings. 
 
using System; 
 
class StrDemo {    
  public static void Main() {    
    Console.WriteLine("Line One\nLine Two\nLine Three"); 
    Console.WriteLine("One\tTwo\tThree"); 
    Console.WriteLine("Four\tFive\tSix"); 
 
    // embed quotes 
    Console.WriteLine("\"Why?\", he asked."); 
  }    
}

listing 11
// Demonstrate verbatim literal strings. 
 
using System; 
 
class Verbatim {    
  public static void Main() {    
    Console.WriteLine(@"This is a verbatim 
string literal 
that spans several lines. 
"); 
    Console.WriteLine(@"Here is some tabbed output: 
1	2	3	4 
5	6	7	8 
"); 
    Console.WriteLine(@"Programmers say, ""I like C#."""); 
  }    
}

listing 12
// Demonstrate dynamic initialization.  
  
using System;  
  
class DynInit {  
  public static void Main() {  
    double s1 = 4.0, s2 = 5.0; // length of sides 
  
    // dynamically initialize hypot  
    double hypot = Math.Sqrt( (s1 * s1) + (s2 * s2) ); 
  
    Console.Write("Hypotenuse of triangle with sides " + 
                  s1 + " by " + s2 + " is "); 
 
    Console.WriteLine("{0:#.###}.", hypot); 
 
  }  
}

listing 13
// Demonstrate block scope. 
 
using System; 
 
class ScopeDemo { 
  public static void Main() { 
    int x; // known to all code within Main() 
 
    x = 10; 
    if(x == 10) { // start new scope
      int y = 20; // known only to this block 
 
      // x and y both known here. 
      Console.WriteLine("x and y: " + x + " " + y); 
      x = y * 2; 
    } 
    // y = 100; // Error! y not known here  
 
    // x is still known here. 
    Console.WriteLine("x is " + x); 
  } 
}

listing 14
// Demonstrate lifetime of a variable. 
 
using System; 
 
class VarInitDemo { 
  public static void Main() { 
    int x;  
 
    for(x = 0; x < 3; x++) { 
      int y = -1; // y is initialized each time block is entered 
      Console.WriteLine("y is: " + y); // this always prints -1 
      y = 100;  
      Console.WriteLine("y is now: " + y); 
    } 
  } 
}

listing 15
/*  
   This program attempts to declare a variable 
   in an inner scope with the same name as one 
   defined in an outer scope. 
 
   *** This program will not compile. *** 
*/  
 
using System; 
 
class NestVar {  
  public static void Main() {  
    int count;  
 
    for(count = 0; count < 10; count = count+1) { 
      Console.WriteLine("This is count: " + count);  
     
      int count; // illegal!!! 
      for(count = 0; count < 2; count++) 
        Console.WriteLine("This program is in error!"); 
    } 
  }  
}

listing 16
// Demonstrate automatic conversion from long to double. 
 
using System; 
 
class LtoD {    
  public static void Main() {    
    long L; 
    double D; 
   
    L = 100123285L; 
    D = L; 
   
    Console.WriteLine("L and D: " + L + " " + D); 
  }    
}

listing 17
// *** This program will not compile. *** 
 
using System; 
 
class LtoD {    
  public static void Main() {    
    long L; 
    double D; 
   
    D = 100123285.0; 
    L = D; // Illegal!!! 
   
    Console.WriteLine("L and D: " + L + " " + D); 
   
  }    
}

listing 18
// Demonstrate casting. 
 
using System; 
 
class CastDemo {    
  public static void Main() {    
    double x, y; 
    byte b; 
    int i; 
    char ch; 
    uint u; 
    short s; 
    long l; 
 
    x = 10.0; 
    y = 3.0; 
 
    // cast an int into a double 
    i = (int) (x / y); // cast double to int, fractional component lost 
    Console.WriteLine("Integer outcome of x / y: " + i); 
    Console.WriteLine(); 
     
    // cast an int into a byte, no data lost 
    i = 255; 
    b = (byte) i;  
    Console.WriteLine("b after assigning 255: " + b + 
                      " -- no data lost."); 
 
    // cast an int into a byte, data lost 
    i = 257; 
    b = (byte) i;  
    Console.WriteLine("b after assigning 257: " + b + 
                      " -- data lost."); 
    Console.WriteLine(); 
 
    // cast a uint into a short, no data lost 
    u = 32000; 
    s = (short) u; 
    Console.WriteLine("s after assigning 32000: " + s + 
                      " -- no data lost.");  
 
    // cast a uint into a short, data lost 
    u = 64000; 
    s = (short) u; 
    Console.WriteLine("s after assigning 64000: " + s + 
                      " -- data lost.");  
    Console.WriteLine(); 
 
    // cast a long into a uint, no data lost 
    l = 64000; 
    u = (uint) l; 
    Console.WriteLine("u after assigning 64000: " + u + 
                      " -- no data lost.");  
 
    // cast a long into a uint, data lost 
    l = -12; 
    u = (uint) l; 
    Console.WriteLine("u after assigning -12: " + u + 
                      " -- data lost.");  
    Console.WriteLine(); 
 
    // cast an int into a char 
    b = 88; // ASCII code for X 
    ch = (char) b; 
    Console.WriteLine("ch after assigning 88: " + ch);  
  }    
}

listing 19
// A promotion surprise!  
  
using System;  
  
class PromDemo {     
  public static void Main() {     
    byte b;  
    
    b = 10;  
    b = (byte) (b * b); // cast needed!!  
  
    Console.WriteLine("b: "+ b);  
  }     
}

listing 20
// Using casts in an expression.  
  
using System;  
  
class CastExpr {     
  public static void Main() {     
    double n;  
  
     for(n = 1.0; n <= 10; n++) {  
       Console.WriteLine("The square root of {0} is {1}",  
                         n, Math.Sqrt(n));  
  
       Console.WriteLine("Whole number part: {0}" ,   
                         (int) Math.Sqrt(n));  
   
       Console.WriteLine("Fractional part: {0}",   
                         Math.Sqrt(n) - (int) Math.Sqrt(n) );  
       Console.WriteLine(); 
    }  
  
  }     
}