listing 1
const float version =  3.2;

listing 2
#include <iostream>
using namespace std;

void code(const char *str);
 
int main()
{
  code("this is a test");

  return 0;
}

void code(const char *str)
{
  while(*str) {
    cout << (char) (*str+1);
    str++;
  }
}

listing 3
// This is wrong.
void code(const char *str)
{
  while(*str) {
    *str = *str + 1; // Error, can't modify
    cout << (char) *str;
    str++;
  }
}

listing 4
// const references cannot be modified.
#include <iostream>
using namespace std;

void f(const int &i);

int main()
{
  int k = 10;

  f(k);
  return 0;
}

void f(const int &i)
{
  i = 100; // Error, can't modify a const reference.
  cout <<  i;
}

listing 5
#include <iostream>
using namespace std;

const int size = 10;

int main()
{
  int A1[size], A2[size], A3[size];

  // ...
}

listing 6
int clock, timer;
// ... 
timer = clock;                             // line A
// ... do something
cout << "Elapsed type is " << clock-timer; // line B

listing 7
volatile int clock;

listing 8
const volatile unsigned char *port;

listing 9
int first, last;  /* global definition of first 
                     and last */

int main()
{
  extern int first;  /* optional use of the
                        extern declaration */

  // ...
}

listing 10
static int count;

listing 11
static int count = 200;

listing 12
/* Compute a running average of numbers entered by 
   the user.
*/
#include <iostream>
using namespace std;

int r_avg(int i);

int main()
{
  int num;

  do {
    cout << "Enter numbers (-1 to quit): ";
    cin >> num;
    cout << "Running average is: " << r_avg(num);
    cout << '\n';
  } while(num > -1);

  return 0;
}

int r_avg(int i)
{
  static int sum=0, count=0;

  sum = sum + i;

  count++;

  return sum / count;
}

listing 13
// ---------------------- First File ----------------------

#include <iostream>
using namespace std;

int r_avg(int i);
void reset();

int main()
{
  int num;

  do {
    cout << "Enter numbers (-1 to quit, -2 to reset): ";
    cin >> num;
    if(num==-2) {
      reset();
      continue;
    }
    cout << "Running average is: " << r_avg(num);
    cout << '\n';
  } while(num != -1);

  return 0;
}

// ---------------------- Second File ----------------------

static int sum=0, count=0;

int r_avg(int i)
{
  sum = sum + i;

  count++;

  return sum / count;
}

void reset()
{
  sum = 0;
  count = 0;
}

listing 14
int int_pwr(register int m, register int e)
{
  register int temp;

  temp = 1;
  for( ;e ;e--) temp = temp * m;
  return temp;
}

listing 15
/* This program shows the difference a register variable
   can make to the speed of program execution.
*/

#include <iostream>
#include <ctime> // for older compilers, use <time.h>
using namespace std;

unsigned int i; // non-register 
unsigned int delay;

int main()
{
  register unsigned int j;
  long start, end;

  start = clock();
  for(delay=0; delay<50; delay++)
    for(i=0; i<64000; i++);
  end = clock();
  cout << "Number of clock ticks for non-register loop: ";
  cout << end-start << '\n';

  start = clock();
  for(delay=0; delay<50; delay++)
    for(j=0; j<64000; j++) ;
  end = clock();
  cout << "Number of clock ticks for register loop: ";
  cout << end-start << '\n';

  return 0;
}

listing 16
enum apple {Jonathan, Golden_Del, Red_Del, Winesap,
            Cortland, McIntosh} red, yellow;

listing 17
apple fruit;

listing 18
enum apple fruit;

listing 19
fruit = Winesap;
if(fruit==Red_Del) cout << "Red Delicious\n";

listing 20
cout << Jonathan << ' ' << Cortland;

listing 21
fruit = 1; // Error

listing 22
fruit = (apple) 1; // now OK, but probably poor style

listing 23
enum apple {Jonathan, Golden_Del, Red_Del, Winesap=10,
             Cortland, McIntosh};

listing 24
// This will not print "McIntosh" on the screen.
fruit = McIntosh;
cout << fruit;

listing 25
switch(fruit) {
  case Jonathan: cout << "Jonathan";
    break;
  case Golden_Del: cout << "Golden Delicious";
    break;
  case Red_Del: cout << "Red Delicious";
    break;
  case Winesap: cout << "Winesap";
    break;
  case Cortland: cout << "Cortland";
    break;
  case McIntosh: cout << "McIntosh";
    break;
}

listing 26
#include <iostream>
using namespace std;

enum  apple {Jonathan, Golden_Del, Red_Del, Winesap,
             Cortland, McIntosh};

char name[][20] = {
  "Jonathan",
  "Golden Delicious",
  "Red Delicious",
  "Winesap",
  "Cortland",
  "McIntosh"
};

int main()
{
  apple fruit;

  fruit = Jonathan;
  cout << name[fruit] << '\n';

  fruit = Winesap;
  cout << name[fruit] << '\n';

  fruit = McIntosh;
  cout << name[fruit] << '\n';

  return 0;
}

listing 27
typedef float balance;

listing 28
balance over_due;

listing 29
// Uppercase letters.
#include <iostream>
using namespace std;

int main()
{
  char ch;

  do {
    cin >> ch;

    // This statement turns off the 6th bit. 
    ch = ch & 223; // ch is now uppercase

    cout << ch;
  } while(ch!='Q');

  return 0;
}

listing 30
if(status & 8) cout << "bit 4 is on";

listing 31
// Display the bits within a byte.
void disp_binary(unsigned u)
{
  register int t;

  for(t=128; t>0; t = t/2)
    if(u & t) cout << "1 ";
    else cout << "0 ";
  cout << "\n";
}

listing 32
// Lowercase letters.
#include <iostream>
using namespace std;

int main()
{
  char ch;

  do {
    cin >> ch;

    /* This lowercases the letter by turning
       on bit 6.
    */
    ch = ch | 32;

    cout << ch;
  } while(ch != 'q');

  return 0;
}

listing 33
#include <iostream>
using namespace std;

void disp_binary(unsigned u);

int main()
{
  unsigned u;

  cout << "Enter a number between 0 and 255: ";
  cin >> u;

  cout << "Here's the number in binary: ";
  disp_binary(u);

  cout << "Here's the complement of the number: ";
  disp_binary(~u);

  return 0;
}

// Display the bits within a byte.
void disp_binary(unsigned u)
{
  register int t;

  for(t=128; t>0; t = t/2)
    if(u & t) cout << "1 ";
    else cout << "0 ";
  cout << "\n";
}

listing 34
// Example of bitshifting. 

#include <iostream>
using namespace std;

void disp_binary(unsigned u);

int main()
{
  int i=1, t;

  for(t=0; t<8; t++) {
    disp_binary(i);
    i = i << 1;
  }

  cout << "\n";

  for(t=0; t<8; t++) {
    i = i >> 1;
    disp_binary(i);
  }

  return 0;
}

// Display the bits within a byte.
void disp_binary(unsigned u)
{
  register int t;

  for(t=128; t>0; t=t/2)
    if(u & t) cout << "1 ";
    else cout << "0 ";
  cout << "\n";
}

listing 35
while(something) {
  done = count>0 ? 0 : 1;
  // ...
  if(done) break;
}

listing 36
while(something) {
  if(count>0) done = 0;
  else done = 1;
  // ...
  if(done) break;
}

listing 37
/* This program uses the ? operator to prevent
   a division by zero. */

#include <iostream>
using namespace std;

int div_zero();

int main()
{
  int i, j, result;

  cout << "Enter dividend and divisor: ";
  cin >> i >> j;

  // This statement prevents a divide by zero error.
  result = j ? i/j : div_zero();

  cout << "Result: " << result;

  return 0;
}

int div_zero()
{
  cout << "Cannot divide by zero.\n";
  return 0;
}

listing 38
x = x+10;

listing 39
x += 10;

listing 40
x = x-100;

listing 41
x -= 100;

listing 42
var = (count=19, incr=10, count+1);

listing 43
#include <iostream>
using namespace std;

int main()
{
  int i, j;

  j = 10;

  i = (j++, j+100, 999+j);

  cout << i;

  return 0;
}

listing 44
count = incr = index = 10;

listing 45
// Demonstrate sizeof.
#include <iostream>
using namespace std;

int main()
{
  char ch;
  int i;

  cout << sizeof ch << ' '; // size of char
  cout << sizeof i << ' ';  // size of int
  cout << sizeof (float) << ' '; // size of float
  cout << sizeof (double) << ' '; // size of double

  return 0;
}

listing 46
int nums[4];

cout << sizeof nums; // displays 16

listing 47
#include <iostream>
using namespace std;

int main()
{
  int *p;  

  p = new int; // allocate memory for int
  if(!p) {
    cout << "Allocation Failure\n";
    return 1;
  }

  *p = 20; // assign that memory the value 20
  cout << *p; // prove that it works by displaying value

  delete p; // free the memory

  return 0;
}

listing 48
#include <iostream>
using namespace std;

int main()
{
  int *p;

  p = new int (99);  // initialize with 99
  if(!p) {
    cout << "Allocation Failure\n";
    return 1;
  }

  cout << *p;

  delete p;

  return 0;
}

listing 49
#include <iostream>
using namespace std;

int main()
{
  float *p;
  int i;

  p = new float [10]; // get a 10-element array
  if(!p) {
    cout << "Allocation Failure\n";
    return 1;
  }

  // assign the values 100 through 109
  for(i=0; i<10; i++) p[i] = 100.00 + i;

  // display the contents of the array
  for(i=0; i<10; i++)  cout << p[i] << " ";

  delete [] p; // delete the entire array

  return 0;
}

listing 50
#include <iostream>
#include <cstdlib> // for older compilers, use <stdlib.h>
using namespace std;

int main()
{
  int *i;
  float *j;

  i = (int *) malloc(sizeof(int));
  if(!i) {
    cout << "Allocation Failure.\n";
    return 1;
  }

  j = (float *) malloc(sizeof(float));
  if(!j) {
    cout << "Allocation Failure.\n";
    return 1;
  }

  *i= 10;
  *j = 100.123;

  cout << *i << ' ' << *j;

  // free the memory
  free(i);
  free(j);

  return 0;
}