c_info.txt

这是一个unix 系统下的 C 语言函数大全的电子文章。

      while (!DONE) 
      { 
      status = bioscom(3, 0, COM1); 
      if (status & DATA_READY) 
      if ((out = bioscom(2, 0, COM1) & 0x7F) != 0) 
      putch(out); 
      if (kbhit()) 
      { 
      if ((in = getch()) == '\x1B') 
      DONE = TRUE; 
      bioscom(1, in, COM1); 
      } 
      } 
      return 0; 
      } 




      函数名: biosdisk 
      功 能: 软硬盘I/O 
      用 法: int biosdisk(int cmd, int drive, int head, int track, int 
      sector 
      int nsects, void *buffer); 
      程序例: 

      #include <bios.h> 
      #include <stdio.h> 

      int main(void) 
      { 
      int result; 
      char buffer[512]; 

      printf("Testing to see if drive a: is ready\n"); 
      result = biosdisk(4,0,0,0,0,1,buffer); 
      result &= 0x02; 
      (result) ? (printf("Drive A: Ready\n")) : 
      (printf("Drive A: Not Ready\n")); 

      return 0; 
      } 




      函数名: biosequip 
      功 能: 检查设备 
      用 法: int biosequip(void); 
      程序例: 

      #include <bios.h> 
      #include <stdio.h> 

      int main(void) 
      { 
      int result; 
      char buffer[512]; 

      printf("Testing to see if drive a: is ready\n"); 
      result = biosdisk(4,0,0,0,0,1,buffer); 
      result &= 0x02; 
      (result) ? (printf("Drive A: Ready\n")) : 
      (printf("Drive A: Not Ready\n")); 

      return 0; 
      } 




      函数名: bioskey 
      功 能: 直接使用BIOS服务的键盘接口 
      用 法: int bioskey(int cmd); 
      程序例: 

      #include <stdio.h> 
      #include <bios.h> 
      #include <ctype.h> 

      #define RIGHT 0x01 
      #define LEFT 0x02 
      #define CTRL 0x04 
      #define ALT 0x08 

      int main(void) 
      { 
      int key, modifiers; 

      /* function 1 returns 0 until a key is pressed */ 
      while (bioskey(1) == 0); 

      /* function 0 returns the key that is waiting */ 
      key = bioskey(0); 

      /* use function 2 to determine if shift keys were used */ 
      modifiers = bioskey(2); 
      if (modifiers) 
      { 
      printf("["); 
      if (modifiers & RIGHT) printf("RIGHT"); 
      if (modifiers & LEFT) printf("LEFT"); 
      if (modifiers & CTRL) printf("CTRL"); 
      if (modifiers & ALT) printf("ALT"); 
      printf("]"); 
      } 
      /* print out the character read */ 
      if (isalnum(key & 0xFF)) 
      printf("'%c'\n", key); 
      else 
      printf("%#02x\n", key); 
      return 0; 
      } 



      函数名: biosmemory 
      功 能: 返回存储块大小 
      用 法:int biosmemory(void); 
      程序例: 

      #include <stdio.h> 
      #include <bios.h> 

      int main(void) 
      { 
      int memory_size; 

      memory_size = biosmemory(); /* returns value up to 640K */ 
      printf("RAM size = %dK\n",memory_size); 
      return 0; 
      } 




      函数名: biosprint 
      功 能: 直接使用BIOS服务的打印机I/O 
      用 法: int biosprint(int cmd, int byte, int port); 
      程序例: 

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

      int main(void) 
      { 
      #define STATUS 2 /* printer status command */ 
      #define PORTNUM 0 /* port number for LPT1 */ 

      int status, abyte=0; 

      printf("Please turn off your printer. Press any key to 
      continue\n"); 
      getch(); 
      status = biosprint(STATUS, abyte, PORTNUM); 
      if (status & 0x01) 
      printf("Device time out.\n"); 
      if (status & 0x08) 
      printf("I/O error.\n"); 

      if (status & 0x10) 
      printf("Selected.\n"); 
      if (status & 0x20) 
      printf("Out of paper.\n"); 

      if (status & 0x40) 
      printf("Acknowledge.\n"); 
      if (status & 0x80) 
      printf("Not busy.\n"); 

      return 0; 
      } 




      函数名: biostime 
      功 能: 读取或设置BIOS时间 
      用 法: long biostime(int cmd, long newtime); 
      程序例: 

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

      int main(void) 
      { 
      long bios_time; 

      clrscr(); 
      cprintf("The number of clock ticks since midnight is:\r\n"); 
      cprintf("The number of seconds since midnight is:\r\n"); 
      cprintf("The number of minutes since midnight is:\r\n"); 
      cprintf("The number of hours since midnight is:\r\n"); 
      cprintf("\r\nPress any key to quit:"); 
      while(!kbhit()) 
      { 
      bios_time = biostime(0, 0L); 

      gotoxy(50, 1); 
      cprintf("%lu", bios_time); 

      gotoxy(50, 2); 
      cprintf("%.4f", bios_time / CLK_TCK); 

      gotoxy(50, 3); 
      cprintf("%.4f", bios_time / CLK_TCK / 60); 

      gotoxy(50, 4); 
      cprintf("%.4f", bios_time / CLK_TCK / 3600); 
      } 
      return 0; 
      } 




      函数名: brk 
      功 能: 改变数据段空间分配 
      用 法: int brk(void *endds); 
      程序例: 

      #include <stdio.h> 
      #include <alloc.h> 

      int main(void) 
      { 
      char *ptr; 

      printf("Changing allocation with brk()\n"); 
      ptr = malloc(1); 
      printf("Before brk() call: %lu bytes free\n", coreleft()); 
      brk(ptr+1000); 
      printf(" After brk() call: %lu bytes free\n", coreleft()); 
      return 0; 
      } 




      函数名: bsearch 
      功 能: 二分法搜索 
      用 法: void *bsearch(const void *key, const void *base, size_t 
      *nelem, 
      size_t width, int(*fcmp)(const void *, const *)); 
      程序例: 

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

      #define NELEMS(arr) (sizeof(arr) / sizeof(arr[0])) 

      int numarray[] = {123, 145, 512, 627, 800, 933}; 

      int numeric (const int *p1, const int *p2) 
      { 
      return(*p1 - *p2); 
      } 

      int lookup(int key) 
      { 
      int *itemptr; 

      /* The cast of (int(*)(const void *,const void*)) 
      is needed to avoid a type mismatch error at 
      compile time */ 
      itemptr = bsearch (&key, numarray, NELEMS(numarray), 
      sizeof(int), (int(*)(const void *,const void *))numeric); 
      return (itemptr != NULL); 
      } 

      int main(void) 
      { 
      if (lookup(512)) 
      printf("512 is in the table.\n"); 
      else 
      printf("512 isn't in the table.\n"); 

      return 0; 
      } 
      函数名: cabs 
      功 能: 计算复数的绝对值 
      用 法: double cabs(struct complex z); 
      程序例: 
      #include <stdio.h> 
      #include <math.h> 

      int main(void) 
      { 
      struct complex z; 
      double val; 

      z.x = 2.0; 
      z.y = 1.0; 
      val = cabs(z); 

      printf("The absolute value of %.2lfi %.2lfj is %.2lf", z.x, 
      z.y, val); 
      return 0; 
      } 




      函数名: calloc 
      功 能: 分配主存储器 
      用 法: void *calloc(size_t nelem, size_t elsize); 
      程序例: 

      #include <stdio.h> 
      #include <alloc.h> 

      int main(void) 
      { 
      char *str = NULL; 

      /* allocate memory for string */ 
      str = calloc(10, sizeof(char)); 

      /* copy "Hello" into string */ 
      strcpy(str, "Hello"); 

      /* display string */ 
      printf("String is %s\n", str); 

      /* free memory */ 
      free(str); 

      return 0; 
      } 




      函数名: ceil 
      功 能: 向上舍入 
      用 法: double ceil(double x); 
      程序例: 

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

      int main(void) 
      { 
      double number = 123.54; 
      double down, up; 

      down = floor(number); 
      up = ceil(number); 

      printf("original number %5.2lf\n", number); 
      printf("number rounded down %5.2lf\n", down); 
      printf("number rounded up %5.2lf\n", up); 

      return 0; 
      } 




      函数名: cgets 
      功 能: 从控制台读字符串 
      用 法: char *cgets(char *str); 
      程序例: 

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

      int main(void) 
      { 
      char buffer[83]; 
      char *p; 

      /* There's space for 80 characters plus the NULL terminator */ 

      buffer[0] = 81; 

      printf("Input some chars:"); 
      p = cgets(buffer); 
      printf("\ncgets read %d characters: \"%s\"\n", buffer[1], p); 
      printf("The returned pointer is %p, buffer[0] is at %p\n", p, 
      &buffer); 

      /* Leave room for 5 characters plus the NULL terminator */ 
      buffer[0] = 6; 

      printf("Input some chars:"); 
      p = cgets(buffer); 
      printf("\ncgets read %d characters: \"%s\"\n", buffer[1], p); 
      printf("The returned pointer is %p, buffer[0] is at %p\n", p, 
      &buffer); 
      return 0; 
      } 




      函数名: chdir 
      功 能: 改变工作目录 
      用 法: int chdir(const char *path); 
      程序例: 

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

      char old_dir[MAXDIR]; 
      char new_dir[MAXDIR]; 

      int main(void) 
      { 
      if (getcurdir(0, old_dir)) 
      { 
      perror("getcurdir()"); 
      exit(1); 
      } 
      printf("Current directory is: \\%s\n", old_dir); 

      if (chdir("\\")) 
      { 
      perror("chdir()"); 
      exit(1); 
      } 

      if (getcurdir(0, new_dir)) 
      { 
      perror("getcurdir()"); 
      exit(1); 
      } 
      printf("Current directory is now: \\%s\n", new_dir); 

      printf("\nChanging back to orignal directory: \\%s\n", 
      old_dir); 
      if (chdir(old_dir)) 
      { 
      perror("chdir()"); 
      exit(1); 
      } 

      return 0; 
      } 



      函数名: _chmod, chmod 
      功 能: 改变文件的访问方式 
      用 法: int chmod(const char *filename, int permiss); 
      程序例: 

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

      void make_read_only(char *filename); 

      int main(void) 
      { 
      make_read_only("NOTEXIST.FIL"); 
      make_read_only("MYFILE.FIL"); 
      return 0; 
      } 

      void make_read_only(char *filename) 
      { 
      int stat; 

      stat = chmod(filename, S_IREAD); 
      if (stat) 
      printf("Couldn't make %s read-only\n", filename); 
      else 
      printf("Made %s read-only\n", filename); 
      } 




      函数名: chsize 
      功 能: 改变文件大小 
      用 法: int chsize(int handle, long size); 
      程序例: 

      #include <string.h> 
      #include <fcntl.h> 
      #include <io.h> 

      int main(void) 
      { 
      int handle; 
      char buf[11] = "0123456789"; 

      /* create text file containing 10 bytes */ 
      handle = open("DUMMY.FIL", O_CREAT); 
      write(handle, buf, strlen(buf)); 

      /* truncate the file to 5 bytes in size */ 
      chsize(handle, 5); 

      /* close the file */ 
      close(handle); 
      return 0; 
      } 



      函数名: circle 
      功 能: 在给定半径以(x, y)为圆心画圆 
      用 法: void far circle(int x, int y, int radius); 
      程序例: 

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

      int main(void) 
      { 
      /* request auto detection */ 
      int gdriver = DETECT, gmode, errorcode; 
      int midx, midy; 
      int radius = 100; 

      /* 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 */ 
      } 

      midx = getmaxx() / 2; 
      midy = getmaxy() / 2; 
      setcolor(getmaxcolor()); 

      /* draw the circle */ 
      circle(midx, midy, radius); 

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




      函数名: cleardevice 
      功 能: 清除图形屏幕 
      用 法: void far cleardevice(void); 
      程序例: 

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

      int main(void) 
      { 
      /* request auto detection */ 
      int gdriver = DETECT, gmode, errorcode; 
      int midx, midy; 

      /* 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 */ 
      } 

      midx = getmaxx() / 2; 
      midy = getmaxy() / 2; 
      setcolor(getmaxcolor()); 

      /* for centering screen messages */ 
      settextjustify(CENTER_TEXT, CENTER_TEXT); 

      /* output a message to the screen */ 
      outtextxy(midx, midy, "press any key to clear the screen:"); 

      /* wait for a key */ 
      getch(); 

      /* clear the screen */ 
      cleardevice(); 

      /* output another message */ 
      outtextxy(midx, midy, "press any key to quit:"); 

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