CHAP4.LST

listing 1
// Demonstrate the basic arithmetic operators.
class BasicMath {
  public static void main(String args[]) {
    // arithmetic using integers
    System.out.println("Integer Arithmetic");
    int a = 1 + 1;
    int b = a * 3;
    int c = b / 4;
    int d = c - a;
    int e = -d;
    System.out.println("a = " + a);
    System.out.println("b = " + b);
    System.out.println("c = " + c);
    System.out.println("d = " + d);
    System.out.println("e = " + e);

    // arithmetic using doubles
    System.out.println("\nFloating Point Arithmetic");
    double da = 1 + 1;
    double db = da * 3;
    double dc = db / 4;
    double dd = dc - a;
    double de = -dd;
    System.out.println("da = " + da);
    System.out.println("db = " + db);
    System.out.println("dc = " + dc);
    System.out.println("dd = " + dd);
    System.out.println("de = " + de);
  }
}

listing 2
// Demonstrate the % operator.
class Modulus {
  public static void main(String args[]) {
    int x = 42;
    double y = 42.25;

    System.out.println("x mod 10 = " + x % 10);
    System.out.println("y mod 10 = " + y % 10);
  }
}

listing 3
a = a + 4;

listing 4
a += 4;

listing 5
a = a % 2;

listing 6
a %= 2;

listing 7
// Demonstrate several assignment operators.
class OpEquals {
  public static void main(String args[]) {
    int a = 1;
    int b = 2;
    int c = 3;

    a += 5;
    b *= 4;
    c += a * b;
    c %= 6;
    System.out.println("a = " + a);
    System.out.println("b = " + b);
    System.out.println("c = " + c);
  }
}

listing 8
x = x + 1;

listing 9
x++;

listing 10
x = x - 1;

listing 11
x--;

listing 12
x = 42;
y = ++x;

listing 13
x = x + 1;
y = x;

listing 14
x = 42;
y = x++;

listing 15
y = x;
x = x + 1;

listing 16
// Demonstrate ++ and --.
class IncDec {
  public static void main(String args[]) {
    int a = 1;
    int b = 2;
    int c;
    int d;

    c = ++b;
    d = a++;
    c++;
    System.out.println("a = " + a);
    System.out.println("b = " + b);
    System.out.println("c = " + c);
    System.out.println("d = " + d);
  }
}

listing 17
// Demonstrate the bitwise logical operators.
class BitLogic {
  public static void main(String args[]) {
    String binary[] = {
      "0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111",
      "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"
    };
    int a = 3; // 0 + 2 + 1 or 0011 in binary
    int b = 6; // 4 + 2 + 0 or 0110 in binary
    int c = a | b;
    int d = a & b;
    int e = a ^ b;
    int f = (~a & b) | (a & ~b);
    int g = ~a & 0x0f;

    System.out.println("        a = " + binary[a]);
    System.out.println("        b = " + binary[b]);
    System.out.println("      a|b = " + binary[c]);
    System.out.println("      a&b = " + binary[d]);
    System.out.println("      a^b = " + binary[e]);
    System.out.println("~a&b|a&~b = " + binary[f]);
    System.out.println("       ~a = " + binary[g]);
  }
}

listing 18
// Left shifting a byte value.
class ByteShift {
  public static void main(String args[]) {
    byte a = 64, b;
    int i;

    i = a << 2;
    b = (byte) (a << 2);

    System.out.println("Original value of a: " + a);
    System.out.println("i and b: " + i + " " + b);
  }
}

listing 19
// Left shifting as a quick way to multiply by 2.
class MultByTwo {
  public static void main(String args[]) {
    int i;
    int num = 0xFFFFFFE;

    for(i=0; i<4; i++) {
      num = num << 1;
      System.out.println(num);
    }
  }
}

listing 20
int a = 32;
a = a >> 2; // a now contains 8

listing 21
int a = 35;
a = a >> 2; // a still contains 8

listing 22
// Masking sign extension.
class HexByte {
  static public void main(String args[]) {
    char hex[] = {
      '0', '1', '2', '3', '4', '5', '6', '7',
      '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
    };
    byte b = (byte) 0xf1;

    System.out.println("b = 0x" + hex[(b >> 4) & 0x0f] + hex[b & 0x0f]);
  }
}

listing 23
int a = -1;
a = a >>> 24;

listing 24
// Unsigned shifting a byte value.
class ByteUShift {
  static public void main(String args[]) {
    char hex[] = {
      '0', '1', '2', '3', '4', '5', '6', '7',
      '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
    };
    byte b = (byte) 0xf1;
    byte c = (byte) (b >> 4);
    byte d = (byte) (b >>> 4);
    byte e = (byte) ((b & 0xff) >> 4);

    System.out.println("              b = 0x"
      + hex[(b >> 4) & 0x0f] + hex[b & 0x0f]);
    System.out.println("         b >> 4 = 0x"
      + hex[(c >> 4) & 0x0f] + hex[c & 0x0f]);
    System.out.println("        b >>> 4 = 0x"
      + hex[(d >> 4) & 0x0f] + hex[d & 0x0f]);
    System.out.println("(b & 0xff) >> 4 = 0x"
      + hex[(e >> 4) & 0x0f] + hex[e & 0x0f]);
  }
}

listing 25
a = a >> 4;
a >>= 4;

listing 26
a = a | b;
a |= b;

listing 27
class OpBitEquals {
  public static void main(String args[]) {
    int a = 1;
    int b = 2;
    int c = 3;

    a |= 4;
    b >>= 1;
    c <<= 1;
    a ^= c;
    System.out.println("a = " + a);
    System.out.println("b = " + b);
    System.out.println("c = " + c);
  }
}

listing 28
int a = 4;
int b = 1;
boolean c = a < b;

listing 29
int done;
// ...
if(!done) ... // Valid in C/C++
if(num) ...   // but not in Java.

listing 30
if(done == 0)) ... // This is Java-style.
if(num != 0) ...

listing 31
// Demonstrate the boolean logical operators.
class BoolLogic {
  public static void main(String args[]) {
    boolean a = true;
    boolean b = false;
    boolean c = a | b;
    boolean d = a & b;
    boolean e = a ^ b;
    boolean f = (!a & b) | (a & !b);
    boolean g = !a;

    System.out.println("        a = " + a);
    System.out.println("        b = " + b);
    System.out.println("      a|b = " + c);
    System.out.println("      a&b = " + d);
    System.out.println("      a^b = " + e);
    System.out.println("!a&b|a&!b = " + f);
    System.out.println("       !a = " + g);
  }
}

listing 32
if (denom != 0 && num / denom > 10)

listing 33
if(c==1 & e++ < 100) d = 100;

listing 34
int x, y, z;

x = y = z = 100; // set x, y, and z to 100

listing 35
ratio = denom == 0 ? 0 : num / denom;

listing 36
// Demonstrate ?. 
class Ternary {
  public static void main(String args[]) {
    int i, k;

    i = 10;
    k = i < 0 ? -i : i; // get absolute value of i
    System.out.print("Absolute value of ");
    System.out.println(i + " is " + k);

    i = -10;
    k = i < 0 ? -i : i; // get absolute value of i
    System.out.print("Absolute value of ");
    System.out.println(i + " is " + k);
  }
}

listing 37
a >> b + 3

listing 38
a >> (b + 3)

listing 39
(a >> b) + 3

listing 40
a | 4 + c >> b & 7 || b > a % 3
(a | (((4 + c) >> b) & 7)) || (b > (a % 3))