chap7.lst

Borland C++ Builder The Complete Reference 例程源代码

listing 1
struct addr { 
  char name[30]; 
  char street[40]; 
  char city[20]; 
  char state[3]; 
  char zip[11]; 
  int customer_num; 
};

listing 2
struct addr addr_info;

listing 3
struct addr { 
  char name[30]; 
  char street[40]; 
  char city[20]; 
  char state[3]; 
  char zip[11]; 
  int customer_num; 
} addr_info, binfo, cinfo;

listing 4
struct { 
  char name[30]; 
  char street[40]; 
  char city[20]; 
  char state[3]; 
  char zip[11]; 
  int customer_num; 
} addr_info;

listing 5
addr_info.customer_num = 88;

listing 6
printf("%d", addr_info.customer_num);

listing 7
gets(addr_info.name);

listing 8
register int t; 
for(t=0; addr_info.name[t]; ++t) putchar(addr_info.name[t]);

listing 9
#include <stdio.h> 
 
int main(void) 
{ 
  struct { 
    int a; 
    int b; 
  } x, y; 
 
  x.a = 10; 
  x.b = 20; 
 
  y = x; /* assign one structure to another */ 
  printf("Contents of y: %d %d.", y.a, y.b); 
 
  return 0; 
}

listing 10
struct addr addr_info[100];

listing 11
printf("%s", addr_info[2].zip);

listing 12
#define MAX 100 
 
struct inv { 
  char item[30]; 
  float cost; 
  int on_hand; 
} inv_info[MAX];

listing 13
int main(void) 
{ 
  char choice; 
 
  init_list(); /* initialize the structure array */ 
  for(;;) { 
    choice = menu_select(); 
    switch(choice) { 
      case 1: enter(); 
        break; 
      case 2: del(); 
        break; 
      case 3: list(); 
        break; 
      case 4: return 0; 
    } 
  } 
}

listing 14
/* Initialize the structure array. */ 
void init_list(void) 
{ 
  register int t; 
 
  for(t=0; t<MAX; ++t) inv_info[t].item[0] = '\0'; 
}

listing 15
/* Input the user's selection. */ 
int menu_select(void) 
{ 
  char s[80]; 
  int c; 
 
  printf("\n"); 
  printf("1. Enter an item\n"); 
  printf("2. Remove an item\n"); 
  printf("3. List the inventory\n"); 
  printf("4. Quit\n"); 
  do { 
    printf("\nEnter your choice: "); 
    gets(s); 
    c = atoi(s); 
  } while(c<0 || c>4); 
  return c; 
}

listing 16
/* Input the inventory information. */ 
void enter(void) 
{ 
  int slot; 
 
  slot = find_free(); 
  if(slot == -1) { 
    printf("\nList Full"); 
    return; 
  } 
 
  printf("Enter item: "); 
  gets(inv_info[slot].item); 
 
  printf("Enter cost: "); 
  scanf("%f", &inv_info[slot].cost); 
 
  printf("Enter number on hand: "); 
  scanf("%d%*c",&inv_info[slot].on_hand); 
} 
 
/* Return the index of the first unused array 
   location or -1 if no free locations exist. 
*/ 
int find_free(void) 
{ 
  register int t; 
 
  for(t=0; inv_info[t].item[0] && t<MAX; ++t) ; 
  if(t == MAX) return -1; /* no slots free */ 
  return t; 
}

listing 17
/* Remove an item from the list. */ 
void del(void) 
{ 
  register int slot; 
  char s[80]; 
 
  printf("enter record #: "); 
  gets(s); 
  slot = atoi(s); 
  if(slot >= 0 && slot < MAX) inv_info[slot].item[0] = '\0'; 
}

listing 18
/* Display the list on the screen. */ 
void list(void) 
{ 
  register int t; 
 
  for(t=0; t<MAX; ++t) { 
    if(inv_info[t].item[0]) { 
      printf("Item: %s\n", inv_info[t].item); 
      printf("Cost: %f\n", inv_info[t].cost); 
      printf("On hand: %d\n\n", inv_info[t].on_hand); 
    } 
  } 
  printf("\n\n"); 
}

listing 19
/* A simple inventory program using an array of structures */ 
 
#include <stdio.h> 
#include <stdlib.h> 
 
#define MAX 100 
 
struct inv { 
  char item[30]; 
  float cost; 
  int on_hand; 
} inv_info[MAX]; 
 
void init_list(void), list(void), del(void); 
void enter(void); 
int menu_select(void), find_free(void); 
 
int main(void) 
{ 
  char choice; 
 
  init_list(); /* initialize the structure array */ 
  for(;;) { 
    choice = menu_select(); 
    switch(choice) { 
      case 1: enter(); 
        break; 
      case 2: del(); 
        break; 
      case 3: list(); 
        break; 
      case 4: return 0; 
    } 
  } 
} 
 
/* Initialize the structure array. */ 
void init_list(void) 
{ 
  register int t; 
 
  for(t=0; t<MAX; ++t) inv_info[t].item[0] = '\0'; 
} 
 
/* Input the user's selection. */ 
int menu_select(void) 
{ 
  char s[80]; 
  int c; 
 
  printf("\n"); 
  printf("1. Enter an item\n"); 
  printf("2. Remove an item\n"); 
  printf("3. List the inventory\n"); 
  printf("4. Quit\n"); 
  do { 
    printf("\nEnter your choice: "); 
    gets(s); 
    c = atoi(s); 
  } while(c<0 || c>4); 
  return c; 
} 
 
/* Input the inventory information. */ 
void enter(void) 
{ 
  int slot; 
 
  slot = find_free(); 
  if(slot == -1) { 
    printf("\nList Full"); 
    return; 
  } 
 
  printf("Enter item: "); 
  gets(inv_info[slot].item); 
 
  printf("Enter cost: "); 
  scanf("%f", &inv_info[slot].cost); 
 
  printf("Enter number on hand: "); 
  scanf("%d%*c", &inv_info[slot].on_hand); 
} 
 
/* Return the index of the first unused array 
   location or -1 if no free locations exist. 
*/ 
int find_free(void) 
{ 
  register int t; 
 
  for(t=0; inv_info[t].item[0] && t<MAX; ++t) ; 
  if(t == MAX) return -1; /* no slots free */ 
  return t; 
} 
 
/* Remove an item from the list. */ 
void del(void) 
{ 
  register int slot; 
  char s[80]; 
 
  printf("enter record #: "); 
  gets(s); 
  slot = atoi(s); 
  if(slot >= 0 && slot < MAX) inv_info[slot].item[0] = '\0'; 
} 
 
/* Display the list on the screen. */ 
void list(void) 
{ 
  register int t; 
 
  for(t=0; t<MAX; ++t) { 
    if(inv_info[t].item[0]) { 
      printf("Item: %s\n", inv_info[t].item); 
      printf("Cost: %f\n", inv_info[t].cost); 
      printf("On hand: %d\n\n", inv_info[t].on_hand); 
    } 
  } 
  printf("\n\n"); 
}

listing 20
struct fred { 
  char x; 
  int y; 
  float z; 
  char s[10]; 
} mike;

listing 21
func(mike.x);    /* passes character value of x */ 
func2(mike.y);   /* passes integer value of y */ 
func3(mike.z);   /* passes float value of z */ 
func4(mike.s);   /* passes address of string s */ 
func(mike.s[2]); /* passes character value of s[2] */

listing 22
func(&mike.x);    /* passes address of character x */ 
func2(&mike.y);   /* passes address of integer y */ 
func3(&mike.z);   /* passes address of float z */ 
func4(mike.s);    /* passes address of string s */ 
func(&mike.s[2]); /* passes address of character s[2] */

listing 23
#include <stdio.h> 
 
/* declare a structure type */ 
struct struct_type { 
  int a, b; 
  char ch; 
}; 
 
void f1(struct struct_type parm); 
 
int main(void) 
{ 
  struct struct_type arg;  /* declare arg */ 
 
  arg.a = 1000; 
  f1(arg); 
 
  return 0; 
} 
 
void f1(struct struct_type parm) 
{ 
  printf("%d", parm.a); 
}

listing 23
struct addr *addr_pointer;

listing 24
struct bal { 
  float balance; 
  char name[80]; 
} person; 
 
struct bal *p;  /* declare a structure pointer */

listing 25
p = &person;

listing 26
p->balance

listing 27
/* Display a software timer. */ 
 
#include <stdio.h> 
#include <conio.h> 
 
#define DELAY 128000 
 
struct my_time { 
  int hours; 
  int minutes; 
  int seconds; 
}; 
 
void update(struct my_time *t), display(struct my_time *t); 
void mydelay(void); 
 
int main(void)  
{ 
  struct my_time systime; 
 
  systime.hours = 0; 
  systime.minutes = 0; 
  systime.seconds = 0; 
 
  for(;;) { 
    update(&systime); 
    display(&systime); 
    if(kbhit()) return 0; 
  } 
} 
 
void update(struct my_time *t) 
{ 
  t->seconds++; 
  if(t->seconds==60) { 
    t->seconds = 0; 
    t->minutes++; 
  } 
  if(t->minutes==60) { 
    t->minutes = 0; 
    t->hours++; 
  } 
  if(t->hours==24) t->hours = 0; 
  mydelay(); 
} 
 
void display(struct my_time *t) 
{ 
  printf("%02d:", t->hours); 
  printf("%02d:", t->minutes); 
  printf("%02d\n", t->seconds); 
} 
 
void mydelay(void) 
{ 
  long int t; 
 
  for(t=1; t<DELAY; ++t) ; 
}

listing 29
if(t->hours==24) t->hours = 0;

listing 28
/* A generalized input example using structure pointers. */ 
 
#include <stdio.h> 
#include <conio.h> 
#include <string.h> 
 
struct xyinput { 
  int x, y; /* screen location for prompt */ 
  char message[80]; /* prompting message */ 
  int i; /* input value */ 
} ; 
 
void input_xy(struct xyinput *info); 
 
int main(void) 
{ 
  struct xyinput mess; 
 
  mess.x = 10; mess.y = 10; 
  strcpy(mess.message, "Enter an integer: "); 
  clrscr(); 
  input_xy(&mess); 
  printf("Your number squared is: %d.", mess.i*mess.i); 
 
  return 0; 
} 
 
/* Display a prompting message at the specified location 
   and input an integer value. 
*/ 
void input_xy(struct xyinput *info) 
{ 
  gotoxy(info->x, info->y); 
  printf(info->message); 
  scanf("%d", &info->i); 
}

listing 29
struct x { 
  int a[10][10]; /* 10 x 10 array of ints */ 
  float b; 
} y;

listing 30
y.a[3][7]

listing 31
struct emp { 
  struct addr address; 
  float wage; 
} worker;

listing 32
worker.wage = 65000.00; 
strcpy(worker.address.zip,"98765");

listing 33
struct device { 
  unsigned int active : 1; 
  unsigned int ready : 1; 
  unsigned int xmt_error : 1; 
} dev_code;

listing 34
void wr_tape(char c) 
{ 
  while(!dev_code.ready) rd(&dev_code); /* wait */ 
  wr_to_tape(c); /* write out byte */ 
 
  while(dev_code.active) rd(&dev_code); /* wait until info is written */ 
  if(dev_code.xmt_error) printf("Write Error"); 
}

listing 35
struct device { 
  unsigned active : 1; 
  unsigned ready : 1; 
  unsigned xmt_error : 1; 
  unsigned : 2; 
  unsigned EOT : 1; 
} dev_code;

listing 36
struct emp { 
  struct addr address; 
  float pay; 
  unsigned lay_off:1;  /* lay off or active */ 
  unsigned hourly:1;   /* hourly pay or wage */ 
  unsigned deductions:3; /* IRS deductions */ 
};

listing 37
union union_type { 
  int i; 
  char ch; 
} ;

listing 38
union union_type cnvt;

listing 39
cnvt.i = 10;

listing 40
union pw { 
  int i; 
  char ch[4]; 
};

listing 41
#include <stdio.h> 
#include <stdlib> 
 
union pw { 
  int i; 
  char ch[4]; 
}; 
 
int write_int(int num, FILE *fp); 
 
int main() 
{ 
  FILE *fp; 
 
  fp = fopen("test.tmp", "w+"); 
  if(fp==NULL) { 
    printf("Cannot open file.\n"); 
    exit(1); 
  } 
  write_int(1000, fp); 
  fclose(fp); 
 
  return 0; 
} 
 
/* write an integer using union */ 
int write_int(int num, FILE *fp) 
{ 
  union pw wrd; 
 
  wrd.i = num; 
  putc(wrd.ch[0], fp); /* write first byte */ 
  putc(wrd.ch[1], fp); /* write second byte */ 
  putc(wrd.ch[2], fp); /* write third byte */ 
  return putc(wrd.ch[3], fp); /* writes last byte */ 
}

listing 42
enum coin { penny, nickel, dime, quarter, 
            half_dollar, dollar}; 
 
enum coin money;

listing 43
money = dime; 
if(money==quarter) printf("is a quarter\n");

listing 44
printf("The value of quarter is %d ", quarter);

listing 45
printf("%d %d", penny, dime);

listing 46
enum coin { penny, nickel, dime, quarter=100, 
            half_dollar, dollar};

listing 47
/* This will not work. */ 
money = dollar; 
printf("%s", money);

listing 48
/* This code will not work. */ 
money = "penny";

listing 49
switch(money) { 
  case penny: printf("penny"); 
     break; 
  case nickel: printf("nickel"); 
     break; 
  case dime: printf("dime"); 
     break; 
  case quarter: printf("quarter"); 
     break; 
  case half_dollar: printf("half_dollar"); 
     break; 
  case dollar: printf("dollar"); 
}

listing 50
char name[][12]={ 
  "penny", 
  "nickel", 
  "dime", 
  "quarter", 
  "half_dollar", 
  "dollar" 
}; 
/* ... */ 
printf("%s", name[money]);

listing 51
char ch; 
int i; 
float f; 
 
printf("%d\n", sizeof ch); 
printf("%d\n", sizeof i); 
printf("%d\n", sizeof f); 
printf("%d\n", sizeof(long double));

listing 52
struct s { 
  char ch; 
  int i; 
  float f; 
} s_var;

listing 53
union u { 
  char ch; 
  int i; 
  float f; 
} u_var;

listing 54
typedef float balance;

listing 55
balance past_due;

listing 56
typedef struct { 
  float due; 
  int over_due; 
  char name[40]; 
} client;  /* here client is the new type name */ 
 
client clist[NUM_CLIENTS]; /* define array of 
                              structures of type client */