wdg_022s.txt

c编程宝典,详细介绍有关c的资料

   /* select a driver and mode that supports */ 
   /* multiple pages.                        */ 
   int gdriver = EGA, gmode = EGAHI, errorcode; 
   int x, y, ht; 

   /* initialize graphics and local variables */ 
   initgraph(&gdriver, &gmode, ""); 

   /* read result of initialization */ 
   errorcode = graphresult(); 
   if (errorcode != grOk)  /* an error occurred */ 
   { 
      printf("Graphics error: %s\n", grapherrormsg(errorcode)); 
      printf("Press any key to halt:"); 
      getch(); 
      exit(1); /* terminate with an error code */ 
   } 

   x = getmaxx() / 2; 
   y = getmaxy() / 2; 
   ht = textheight("W"); 

   /*  select the off screen page for drawing */ 
   setactivepage(1); 

   /* draw a line on page #1 */ 
   line(0, 0, getmaxx(), getmaxy()); 

   /* output a message on page #1 */ 
   settextjustify(CENTER_TEXT, CENTER_TEXT); 
   outtextxy(x, y, "This is page #1:"); 
   outtextxy(x, y+ht, "Press any key to halt:"); 

   /* select drawing to page #0 */ 
   setactivepage(0); 

   /* output a message  on page #0 */ 
   outtextxy(x, y, "This is page #0."); 
   outtextxy(x, y+ht, "Press any key to view page #1:"); 
   getch(); 

   /* select page #1 as the visible page */ 
   setvisualpage(1); 

   /* clean up */ 
   getch(); 
   closegraph(); 
   return 0; 
} 
  
  

函数名: setwritemode 
功  能: 设置图形方式下画线的输出模式 
用  法: void far setwritemode(int mode); 
程序例: 

#include <graphics.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <conio.h> 

int main() 
{ 
   /* request auto detection */ 
   int gdriver = DETECT, gmode, errorcode; 
   int xmax, ymax; 

   /* initialize graphics and local variables */ 
   initgraph(&gdriver, &gmode, ""); 

   /* read result of initialization */ 
   errorcode = graphresult(); 
   if (errorcode != grOk)  /* an error occurred */ 
   { 
      printf("Graphics error: %s\n", grapherrormsg(errorcode)); 
      printf("Press any key to halt:"); 
      getch(); 
      exit(1); /* terminate with an error code */ 
   } 

   xmax = getmaxx(); 
   ymax = getmaxy(); 

   /* select XOR drawing mode */ 
   setwritemode(XOR_PUT); 

   /* draw a line */ 
   line(0, 0, xmax, ymax); 
   getch(); 

   /* erase the line by drawing over it */ 
   line(0, 0, xmax, ymax); 
   getch(); 

   /* select overwrite drawing mode */ 
   setwritemode(COPY_PUT); 

   /* draw a line */ 
   line(0, 0, xmax, ymax); 

   /* clean up */ 
   getch(); 
   closegraph(); 
   return 0; 
} 
  
  

函数名: signal 
功  能: 设置某一信号的对应动作 
用  法: int signal(int sig, sigfun fname); 
程序例: 

/* This example installs a signal handler routine for SIGFPE, 
   catches an integer overflow condition, makes an adjustment 
   to AX register, and returns. This example program MAY cause 
   your computer to crash, and will produce runtime errors 
   depending on which memory model is used. 
*/ 

#pragma inline 
#include <stdio.h> 
#include <signal.h> 

void Catcher(int sig, int type, int *reglist) 
{ 
   printf("Caught it!\n"); 
   *(reglist + 8) = 3;             /* make return AX = 3 */ 
} 

int main(void) 
{ 
   signal(SIGFPE, Catcher); 
   asm     mov     ax,07FFFH       /* AX = 32767 */ 
   asm     inc     ax              /* cause overflow */ 
   asm     into                    /* activate handler */ 

   /* The handler set AX to 3 on return. If that hadn't happened, 
      there would have been another exception when the next 'into' 
      was executed after the 'dec' instruction. */ 
   asm     dec     ax              /* no overflow now */ 
   asm     into                    /* doesn't activate */ 
   return 0; 
} 
  
  
  

函数名: sin 
功  能: 正弦函数 
用  法: double sin(double x); 
程序例: 

#include <stdio.h> 
#include <math.h> 

int main(void) 
{ 
   double result, x = 0.5; 

   result = sin(x); 
   printf("The sin() of %lf is %lf\n", x, result); 
   return 0; 
} 
  
  

函数名: sinh 
功  能: 双曲正弦函数 
用  法: double sinh(double x); 
程序例: 

#include <stdio.h> 
#include <math.h> 

int main(void) 
{ 
   double result, x = 0.5; 

   result = sinh(x); 
   printf("The hyperbolic sin() of %lf is %lf\n", x, result); 
   return 0; 
} 
  
  
  

函数名: sleep 
功  能: 执行挂起一段时间 
用  法: unsigned sleep(unsigned seconds); 
程序例: 

#include <dos.h> 
#include <stdio.h> 

int main(void) 
{ 
   int i; 

   for (i=1; i<5; i++) 
   { 
      printf("Sleeping for %d seconds\n", i); 
      sleep(i); 
   } 
   return 0; 
} 
  
  
  

函数名: sopen 
功  能: 打开一共享文件 
用  法: int sopen(char *pathname, int access, int shflag, int permiss); 
程序例: 

#include <io.h> 
#include <fcntl.h> 
#include <sys\stat.h> 
#include <process.h> 
#include <share.h> 
#include <stdio.h> 

int main(void) 
{ 
   int handle; 
   int status; 

   handle = sopen("c:\\autoexec.bat", O_RDONLY, SH_DENYNO, S_IREAD); 

   if (!handle) 
   { 
      printf("sopen failed\n"); 
      exit(1); 
   } 

   status = access("c:\\autoexec.bat", 6); 
   if (status == 0) 
      printf("read/write access allowed\n"); 
   else 
      printf("read/write access not allowed\n"); 

   close(handle); 
   return 0; 
} 
  
  
  

函数名: sound 
功  能: 以指定频率打开PC扬声器 
用  法: void sound(unsigned frequency); 
程序例: 

/* Emits a 7-Hz tone for 10 seconds. 
   Your PC may not be able to emit a 7-Hz tone. */ 
#include <dos.h> 

int main(void) 
{ 
   sound(7); 
   delay(10000); 
   nosound(); 
   return 0; 
} 
  
  
  

函数名: spawnl 
功  能: 创建并运行子程序 
用  法: int spawnl(int mode, char *pathname, char *arg0, 
     arg1, ... argn, NULL); 
程序例: 

#include <process.h> 
#include <stdio.h> 
#include <conio.h> 

int main(void) 
{ 
   int result; 

   clrscr(); 
   result = spawnl(P_WAIT, "tcc.exe", NULL); 
   if (result == -1) 
   { 
      perror("Error from spawnl"); 
      exit(1); 
   } 
   return 0; 
} 
  
  

函数名: spawnle 
功  能: 创建并运行子程序 
用  法: int spawnle(int mode, char *pathname, char *arg0, 
      arg1,..., argn, NULL); 
程序例: 

/* spawnle() example */ 

#include <process.h> 
#include <stdio.h> 
#include <conio.h> 

int main(void) 
{ 
   int result; 

   clrscr(); 
   result = spawnle(P_WAIT, "tcc.exe", NULL, NULL); 
   if (result == -1) 
   { 
      perror("Error from spawnle"); 
      exit(1); 
   } 
   return 0; 
} 
  
  
  

函数名: sprintf 
功  能: 送格式化输出到字符串中 
用  法: int sprintf(char *string, char *farmat [,argument,...]); 
程序例: 

#include <stdio.h> 
#include <math.h> 

int main(void) 
{ 
   char buffer[80]; 

   sprintf(buffer, "An approximation of Pi is %f\n", M_PI); 
   puts(buffer); 
   return 0; 
} 
  
  

函数名: sqrt 
功  能: 计算平方根 
用  法: double sqrt(double x); 
程序例: 

#include <math.h> 
 #include <stdio.h> 

 int main(void) 
 { 
    double x = 4.0, result; 

    result = sqrt(x); 
    printf("The square root of %lf is %lf\n", x, result); 
    return 0; 
} 
  

函数名: srand 
功  能: 初始化随机数发生器 
用  法: void srand(unsigned seed); 
程序例: 

#include <stdlib.h> 
#include <stdio.h> 
#include <time.h> 

int main(void) 
{ 
   int i; 
   time_t t; 

   srand((unsigned) time(&t)); 
   printf("Ten random numbers from 0 to 99\n\n"); 
   for(i=0; i<10; i++) 
       printf("%d\n", rand() % 100); 
   return 0; 
} 
  
  

函数名: sscanf 
功  能: 执行从字符串中的格式化输入 
用  法: int sscanf(char *string, char *format[,argument,...]); 
程序例: 

#include <stdio.h> 
#include <conio.h> 

int main(void) 
{ 
   char label[20]; 
   char name[20]; 
   int entries = 0; 
   int loop, age; 
   double salary; 

   struct Entry_struct 
   { 
      char  name[20]; 
      int   age; 
      float salary; 
   } entry[20]; 

/* Input a label as a string of characters restricting to 20 characters */ 
   printf("\n\nPlease enter a label for the chart: "); 
   scanf("%20s", label); 
   fflush(stdin);  /* flush the input stream in case of bad input */ 

/* Input number of entries as an integer */ 
   printf("How many entries will there be? (less than 20) "); 
   scanf("%d", &entries); 
   fflush(stdin);   /* flush the input stream in case of bad input */ 

/* input a name restricting input to only letters upper or lower case */ 
   for (loop=0;loop<entries;++loop) 
   { 
      printf("Entry %d\n", loop); 
      printf("  Name   : "); 
      scanf("%[A-Za-z]", entry[loop].name); 
      fflush(stdin);  /* flush the input stream in case of bad input */ 

/* input an age as an integer */ 
      printf("  Age    : "); 
      scanf("%d", &entry[loop].age); 
      fflush(stdin);  /* flush the input stream in case of bad input */ 

/* input a salary as a float */ 
      printf("  Salary : "); 
      scanf("%f", &entry[loop].salary); 
      fflush(stdin); /* flush the input stream in case of bad input */ 
   } 

/* Input a name, age and salary as a string, integer, and double */ 
   printf("\nPlease enter your name, age and salary\n"); 
   scanf("%20s %d %lf", name, &age, &salary); 
  

/* Print out the data that was input */ 
   printf("\n\nTable %s\n",label); 
   printf("Compiled by %s  age %d  $%15.2lf\n", name, age, salary); 
   printf("-----------------------------------------------------\n"); 
   for (loop=0;loop<entries;++loop) 
      printf("%4d | %-20s | %5d | %15.2lf\n", 
         loop + 1, 
  entry[loop].name, 
  entry[loop].age, 
  entry[loop].salary); 
   printf("-----------------------------------------------------\n"); 
   return 0; 
} 
  
  

函数名: stat 
功  能: 读取打开文件信息 
用  法: int stat(char *pathname, struct stat *buff); 
程序例: 

#include <sys\stat.h> 
#include <stdio.h> 
#include <time.h> 

#define FILENAME "TEST.$$$" 

int main(void) 
{ 
   struct stat statbuf; 
   FILE *stream; 

   /* open a file for update */ 
   if ((stream = fopen(FILENAME, "w+")) == NULL) 
   { 
      fprintf(stderr, "Cannot open output file.\n"); 
      return(1); 
   } 

   /* get information about the file */ 
   stat(FILENAME, &statbuf); 

   fclose(stream); 

   /* display the information returned */ 
   if (statbuf.st_mode & S_IFCHR) 
      printf("Handle refers to a device.\n"); 
   if (statbuf.st_mode & S_IFREG) 
      printf("Handle refers to an ordinary file.\n"); 
   if (statbuf.st_mode & S_IREAD) 
      printf("User has read permission on file.\n"); 
   if (statbuf.st_mode & S_IWRITE) 
      printf("User has write permission on file.\n"); 

   printf("Drive letter of file: %c\n", 'A'+statbuf.st_dev); 
   printf("Size of file in bytes: %ld\n", statbuf.st_size); 
   printf("Time file last opened: %s\n", ctime(&statbuf.st_ctime)); 
   return 0; 
} 
  
  
  

函数名: _status87 
功  能: 取浮点状态 
用  法: unsigned int _status87(void); 
程序例: 

#include <stdio.h> 
#include <float.h> 

int main(void) 
{ 
   float x; 
   double y = 1.5e-100; 

   printf("Status 87 before error: %x\n", _status87()); 

   x = y;  /* <-- force an error to occur */ 
   y = x; 

   printf("Status 87 after error : %x\n", _status87()); 
   return 0; 
} 
  
  

函数名: stime 
功  能: 设置时间 
用  法: int stime(long *tp); 
程序例: 

#include <stdio.h> 
#include <time.h> 
#include <dos.h> 

int main(void) 
{ 
   time_t t; 
   struct tm *area; 

   t = time(NULL); 
   area = localtime(&t); 
   printf("Number of seconds since 1/1/1970 is: %ld\n", t); 
   printf("Local time is: %s", asctime(area)); 

   t++; 
   area = localtime(&t); 
   printf("Add a second:  %s", asctime(area)); 

   t += 60; 
   area = localtime(&t); 
   printf("Add a minute:  %s", asctime(area)); 

   t += 3600; 
   area = localtime(&t); 
   printf("Add an hour:   %s", asctime(area)); 

   t += 86400L; 
   area = localtime(&t); 
   printf("Add a day:     %s", asctime(area)); 

   t += 2592000L; 
   area = localtime(&t); 
   printf("Add a month:   %s", asctime(area)); 

   t += 31536000L; 
   area = localtime(&t); 
   printf("Add a year:    %s", asctime(area)); 
   return 0; 
} 
  
  
  

函数名: stpcpy 
功  能: 拷贝一个字符串到另一个 
用  法: char *stpcpy(char *destin, char *source); 
程序例: 

#include <stdio.h> 
#include <string.h> 

int main(void) 
{ 
   char string[10]; 
   char *str1 = "abcdefghi"; 

   stpcpy(string, str1); 
   printf("%s\n", string); 
   return 0; 
}